1
Python 2.3 Quick Reference
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25 Jan 2003 upgraded by Raymond Hettinger for Python 2.3
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16 May 2001 upgraded by Richard Gruet and Simon Brunning for Python 2.0
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2000/07/18 upgraded by Richard Gruet, rgruet@intraware.com for Python 1.5.2
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1995/10/30, by Chris Hoffmann, choffman@vicorp.com
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Python Bestiary, Author: Ken Manheimer, ken.manheimer@nist.gov
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Python manuals, Authors: Guido van Rossum and Fred Drake
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What's new in Python 2.0, Authors: A.M. Kuchling and Moshe Zadka
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python-mode.el, Author: Tim Peters, tim_one@email.msn.com
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and the readers of comp.lang.python
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Python's nest: http://www.python.org Developement: http://
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python.sourceforge.net/ ActivePython : http://www.ActiveState.com/ASPN/
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newsgroup: comp.lang.python Help desk: help@python.org
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Resources: http://starship.python.net/
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http://www.vex.net/parnassus/
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http://aspn.activestate.com/ASPN/Cookbook/Python
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FAQ: http://www.python.org/cgi-bin/faqw.py
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Full documentation: http://www.python.org/doc/
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Excellent reference books:
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Python Essential Reference by David Beazley (New Riders)
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Python Pocket Reference by Mark Lutz (O'Reilly)
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python [-diOStuUvxX?] [-c command | script | - ] [args]
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-c cmd program passed in as string (terminates option list)
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-d Outputs parser debugging information (also PYTHONDEBUG=x)
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-E ignore environment variables (such as PYTHONPATH)
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-h print this help message and exit
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-i Inspect interactively after running script (also PYTHONINSPECT=x) and
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force prompts, even if stdin appears not to be a terminal
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-m mod run library module as a script (terminates option list
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-O optimize generated bytecode (a tad; also PYTHONOPTIMIZE=x)
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-OO remove doc-strings in addition to the -O optimizations
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-Q arg division options: -Qold (default), -Qwarn, -Qwarnall, -Qnew
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-S Don't perform 'import site' on initialization
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-t Issue warnings about inconsistent tab usage (-tt: issue errors)
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-u Unbuffered binary stdout and stderr (also PYTHONUNBUFFERED=x).
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-v Verbose (trace import statements) (also PYTHONVERBOSE=x)
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-W arg : warning control (arg is action:message:category:module:lineno)
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-x Skip first line of source, allowing use of non-unix Forms of #!cmd
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-3 warn about Python 3.x incompatibilities
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-c Specify the command to execute (see next section). This terminates the
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command option list (following options are passed as arguments to the command).
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the name of a python file (.py) to execute read from stdin.
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script Anything afterward is passed as options to python script or command,
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not interpreted as an option to interpreter itself.
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args passed to script or command (in sys.argv[1:])
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If no script or command, Python enters interactive mode.
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* Available IDEs in std distrib: IDLE (tkinter based, portable), Pythonwin
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PYTHONHOME Alternate prefix directory (or prefix;exec_prefix). The
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default module search path uses prefix/lib
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Augments the default search path for module files. The format
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is the same as the shell's $PATH: one or more directory
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pathnames separated by ':' or ';' without spaces around
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PYTHONPATH On Windows first search for Registry key HKEY_LOCAL_MACHINE\
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Software\Python\PythonCore\x.y\PythonPath (default value). You
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may also define a key named after your application with a
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default string value giving the root directory path of your
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If this is the name of a readable file, the Python commands in
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PYTHONSTARTUP that file are executed before the first prompt is displayed in
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interactive mode (no default).
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PYTHONDEBUG If non-empty, same as -d option
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PYTHONINSPECT If non-empty, same as -i option
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PYTHONSUPPRESS If non-empty, same as -s option
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PYTHONUNBUFFERED If non-empty, same as -u option
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PYTHONVERBOSE If non-empty, same as -v option
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PYTHONCASEOK If non-empty, ignore case in file/module names (imports)
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Notable lexical entities
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assert elif from lambda return
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break else global not try
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class except if or while
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continue exec import pass yield
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* (list of keywords in std module: keyword)
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* Illegitimate Tokens (only valid in strings): @ $ ?
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* A statement must all be on a single line. To break a statement over
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multiple lines use "\", as with the C preprocessor.
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Exception: can always break when inside any (), [], or {} pair, or in
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triple-quoted strings.
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* More than one statement can appear on a line if they are separated with
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* Comments start with "#" and continue to end of line.
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(letter | "_") (letter | digit | "_")*
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* Python identifiers keywords, attributes, etc. are case-sensitive.
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* Special forms: _ident (not imported by 'from module import *'); __ident__
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(system defined name);
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__ident (class-private name mangling)
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"a string enclosed by double quotes"
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'another string delimited by single quotes and with a " inside'
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'''a string containing embedded newlines and quote (') marks, can be
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delimited with triple quotes.'''
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""" may also use 3- double quotes as delimiters """
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u'a unicode string' U"Another unicode string"
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r'a raw string where \ are kept (literalized): handy for regular
136
expressions and windows paths!'
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R"another raw string" -- raw strings cannot end with a \
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ur'a unicode raw string' UR"another raw unicode"
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Use \ at end of line to continue a string on next line.
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adjacent strings are concatened, e.g. 'Monty' ' Python' is the same as
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u'hello' + ' world' --> u'hello world' (coerced to unicode)
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String Literal Escapes
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\newline Ignored (escape newline)
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\\ Backslash (\) \e Escape (ESC) \v Vertical Tab (VT)
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\' Single quote (') \f Formfeed (FF) \OOO char with octal value OOO
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\" Double quote (") \n Linefeed (LF)
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\a Bell (BEL) \r Carriage Return (CR) \xHH char with hex value HH
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\b Backspace (BS) \t Horizontal Tab (TAB)
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\uHHHH unicode char with hex value HHHH, can only be used in unicode string
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\UHHHHHHHH unicode char with hex value HHHHHHHH, can only be used in unicode string
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\AnyOtherChar is left as-is
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* NUL byte (\000) is NOT an end-of-string marker; NULs may be embedded in
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* Strings (and tuples) are immutable: they cannot be modified.
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Decimal integer: 1234, 1234567890546378940L (or l)
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Octal integer: 0177, 0177777777777777777 (begin with a 0)
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Hex integer: 0xFF, 0XFFFFffffFFFFFFFFFF (begin with 0x or 0X)
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Long integer (unlimited precision): 1234567890123456
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Float (double precision): 3.14e-10, .001, 10., 1E3
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Complex: 1J, 2+3J, 4+5j (ends with J or j, + separates (float) real and
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* String of length 0, 1, 2 (see above)
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'', '1', "12", 'hello\n'
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* Tuple of length 0, 1, 2, etc:
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() (1,) (1,2) # parentheses are optional if len > 0
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* List of length 0, 1, 2, etc:
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Indexing is 0-based. Negative indices (usually) mean count backwards from end
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Sequence slicing [starting-at-index : but-less-than-index]. Start defaults to
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'0'; End defaults to 'sequence-length'.
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a = (0,1,2,3,4,5,6,7)
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a[1:] ==> (1, 2, 3, 4, 5, 6, 7)
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a[:] ==> (0,1,2,3,4,5,6,7) # makes a copy of the sequence.
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Dictionaries (Mappings)
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{} # Zero length empty dictionary
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{1 : 'first'} # Dictionary with one (key, value) pair
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{1 : 'first', 'next': 'second'}
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dict([('one',1),('two',2)]) # Construct a dict from an item list
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dict('one'=1, 'two'=2) # Construct a dict using keyword args
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dict.fromkeys(['one', 'keys']) # Construct a dict from a sequence
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Operators and their evaluation order
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Operators and their evaluation order
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Highest Operator Comment
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(...) [...] {...} `...` Tuple, list & dict. creation; string
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s[i] s[i:j] s.attr f(...) indexing & slicing; attributes, fct
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+x, -x, ~x Unary operators
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x*y x/y x%y x//y mult, division, modulo, floor division
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x+y x-y addition, subtraction
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x<<y x>>y Bit shifting
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x^y Bitwise exclusive or
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x<y x<=y x>y x>=y x==y x!=y Comparison,
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x is y x is not y membership
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not x boolean negation
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Lowest lambda args: expr anonymous function
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Alternate names are defined in module operator (e.g. __add__ and add for +)
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Most operators are overridable.
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Many binary operators also support augmented assignment:
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x += 1 # Same as x = x + 1
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Basic Types and Their Operations
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Comparisons (defined between *any* types)
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Comparison Meaning Notes
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< strictly less than (1)
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<= less than or equal to
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> strictly greater than
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>= greater than or equal to
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!= or <> not equal to
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is object identity (2)
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is not negated object identity (2)
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Comparison behavior can be overridden for a given class by defining special
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The above comparisons return True or False which are of type bool
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(a subclass of int) and behave exactly as 1 or 0 except for their type and
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that they print as True or False instead of 1 or 0.
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(1) X < Y < Z < W has expected meaning, unlike C
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(2) Compare object identities (i.e. id(object)), not object values.
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Boolean values and operators
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Boolean values and operators
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Value or Operator Returns Notes
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None, numeric zeros, empty sequences and False
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all other values True
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not x True if x is False, else
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x or y if x is False then y, else (1)
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x and y if x is False then x, else (1)
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Truth testing behavior can be overridden for a given class by defining
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special method __nonzero__.
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(1) Evaluate second arg only if necessary to determine outcome.
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None is used as default return value on functions. Built-in single object
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Input that evaluates to None does not print when running Python
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Floats, integers and long integers.
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Floats are implemented with C doubles.
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Integers are implemented with C longs.
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Long integers have unlimited size (only limit is system resources)
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Operators on all numeric types
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Operators on all numeric types
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abs(x) the absolute value of x
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int(x) x converted to integer
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long(x) x converted to long integer
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float(x) x converted to floating point
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x + y the sum of x and y
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x - y difference of x and y
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x * y product of x and y
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x / y quotient of x and y
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x % y remainder of x / y
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divmod(x, y) the tuple (x/y, x%y)
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x ** y x to the power y (the same as pow(x, y))
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Bit operators on integers and long integers
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~x the bits of x inverted
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x ^ y bitwise exclusive or of x and y
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x & y bitwise and of x and y
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x | y bitwise or of x and y
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x << n x shifted left by n bits
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x >> n x shifted right by n bits
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* represented as a pair of machine-level double precision floating point
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* The real and imaginary value of a complex number z can be retrieved through
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the attributes z.real and z.imag.
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raised on application of arithmetic operation to non-number
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numeric bounds exceeded
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raised when zero second argument of div or modulo op
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raised when a floating point operation fails
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Operations on all sequence types (lists, tuples, strings)
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Operations on all sequence types
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Operation Result Notes
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x in s True if an item of s is equal to x, else False
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x not in s False if an item of s is equal to x, else True
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for x in s: loops over the sequence
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s + t the concatenation of s and t
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s * n, n*s n copies of s concatenated
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s[i] i'th item of s, origin 0 (1)
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s[i:j] slice of s from i (included) to j (excluded) (1), (2)
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min(s) smallest item of s
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max(s) largest item of (s)
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iter(s) returns an iterator over s. iterators define __iter__ and next()
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(1) if i or j is negative, the index is relative to the end of the string,
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ie len(s)+ i or len(s)+j is
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substituted. But note that -0 is still 0.
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(2) The slice of s from i to j is defined as the sequence of items with
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index k such that i <= k < j.
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If i or j is greater than len(s), use len(s). If i is omitted, use
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len(s). If i is greater than or
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equal to j, the slice is empty.
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Operations on mutable (=modifiable) sequences (lists)
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Operations on mutable sequences
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Operation Result Notes
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s[i] =x item i of s is replaced by x
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s[i:j] = t slice of s from i to j is replaced by t
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del s[i:j] same as s[i:j] = []
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s.append(x) same as s[len(s) : len(s)] = [x]
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s.count(x) return number of i's for which s[i] == x
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s.extend(x) same as s[len(s):len(s)]= x
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s.index(x) return smallest i such that s[i] == x (1)
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s.insert(i, x) same as s[i:i] = [x] if i >= 0
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s.pop([i]) same as x = s[i]; del s[i]; return x (4)
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s.remove(x) same as del s[s.index(x)] (1)
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s.reverse() reverse the items of s in place (3)
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s.sort([cmpFct]) sort the items of s in place (2), (3)
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(1) raise a ValueError exception when x is not found in s (i.e. out of
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(2) The sort() method takes an optional argument specifying a comparison
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fct of 2 arguments (list items) which should
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return -1, 0, or 1 depending on whether the 1st argument is
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considered smaller than, equal to, or larger than the 2nd
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argument. Note that this slows the sorting process down considerably.
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(3) The sort() and reverse() methods modify the list in place for economy
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of space when sorting or reversing a large list.
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They don't return the sorted or reversed list to remind you of this
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(4) [New 1.5.2] The optional argument i defaults to -1, so that by default the last
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item is removed and returned.
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Operations on mappings (dictionaries)
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Operations on mappings
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Operation Result Notes
404
len(d) the number of items in d
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d[k] the item of d with key k (1)
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d[k] = x set d[k] to x
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del d[k] remove d[k] from d (1)
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d.clear() remove all items from d
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d.copy() a shallow copy of d
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d.get(k,defaultval) the item of d with key k (4)
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d.has_key(k) True if d has key k, else False
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d.items() a copy of d's list of (key, item) pairs (2)
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d.iteritems() an iterator over (key, value) pairs (7)
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d.iterkeys() an iterator over the keys of d (7)
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d.itervalues() an iterator over the values of d (7)
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d.keys() a copy of d's list of keys (2)
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d1.update(d2) for k, v in d2.items(): d1[k] = v (3)
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d.values() a copy of d's list of values (2)
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d.pop(k) remove d[k] and return its value
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d.popitem() remove and return an arbitrary (6)
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d.setdefault(k,defaultval) the item of d with key k (5)
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TypeError is raised if key is not acceptable
426
(1) KeyError is raised if key k is not in the map
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(2) Keys and values are listed in random order
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(3) d2 must be of the same type as d1
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(4) Never raises an exception if k is not in the map, instead it returns
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defaultVal is optional, when not provided and k is not in the map,
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(5) Never raises an exception if k is not in the map, instead it returns
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defaultVal, and adds k to map with value defaultVal. defaultVal is
435
optional. When not provided and k is not in the map, None is returned and
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(6) Raises a KeyError if the dictionary is emtpy.
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(7) While iterating over a dictionary, the values may be updated but
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the keys cannot be changed.
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Operations on strings
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Note that these string methods largely (but not completely) supersede the
444
functions available in the string module.
447
Operations on strings
448
Operation Result Notes
449
s.capitalize() return a copy of s with only its first character
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s.center(width) return a copy of s centered in a string of length width (1)
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s.count(sub[ return the number of occurrences of substring sub in (2)
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,start[,end]]) string s.
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s.decode(([ return a decoded version of s. (3)
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s.encode([ return an encoded version of s. Default encoding is the
459
encoding current default string encoding. (3)
461
s.endswith(suffix return true if s ends with the specified suffix, (2)
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[,start[,end]]) otherwise return False.
463
s.expandtabs([ return a copy of s where all tab characters are (4)
464
tabsize]) expanded using spaces.
465
s.find(sub[,start return the lowest index in s where substring sub is (2)
466
[,end]]) found. Return -1 if sub is not found.
467
s.index(sub[ like find(), but raise ValueError when the substring is (2)
468
,start[,end]]) not found.
469
s.isalnum() return True if all characters in s are alphanumeric, (5)
471
s.isalpha() return True if all characters in s are alphabetic, (5)
473
s.isdigit() return True if all characters in s are digit (5)
474
characters, False otherwise.
475
s.islower() return True if all characters in s are lowercase, False (6)
477
s.isspace() return True if all characters in s are whitespace (5)
478
characters, False otherwise.
479
s.istitle() return True if string s is a titlecased string, False (7)
481
s.isupper() return True if all characters in s are uppercase, False (6)
483
s.join(seq) return a concatenation of the strings in the sequence
484
seq, seperated by 's's.
485
s.ljust(width) return s left justified in a string of length width. (1),
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s.lower() return a copy of s converted to lowercase.
488
s.lstrip() return a copy of s with leading whitespace removed.
489
s.replace(old, return a copy of s with all occurrences of substring (9)
490
new[, maxsplit]) old replaced by new.
491
s.rfind(sub[ return the highest index in s where substring sub is (2)
492
,start[,end]]) found. Return -1 if sub is not found.
493
s.rindex(sub[ like rfind(), but raise ValueError when the substring (2)
494
,start[,end]]) is not found.
495
s.rjust(width) return s right justified in a string of length width. (1),
497
s.rstrip() return a copy of s with trailing whitespace removed.
498
s.split([sep[ return a list of the words in s, using sep as the (10)
499
,maxsplit]]) delimiter string.
500
s.splitlines([ return a list of the lines in s, breaking at line (11)
501
keepends]) boundaries.
502
s.startswith return true if s starts with the specified prefix,
503
(prefix[,start[ otherwise return false. (2)
505
s.strip() return a copy of s with leading and trailing whitespace
507
s.swapcase() return a copy of s with uppercase characters converted
508
to lowercase and vice versa.
509
return a titlecased copy of s, i.e. words start with
510
s.title() uppercase characters, all remaining cased characters
512
s.translate(table return a copy of s mapped through translation table (12)
513
[,deletechars]) table.
514
s.upper() return a copy of s converted to uppercase.
515
s.zfill(width) return a string padded with zeroes on the left side and
516
sliding a minus sign left if necessary. never truncates.
519
(1) Padding is done using spaces.
520
(2) If optional argument start is supplied, substring s[start:] is
521
processed. If optional arguments start and end are supplied, substring s[start:
523
(3) Optional argument errors may be given to set a different error handling
524
scheme. The default for errors is 'strict', meaning that encoding errors raise
525
a ValueError. Other possible values are 'ignore' and 'replace'.
526
(4) If optional argument tabsize is not given, a tab size of 8 characters
528
(5) Returns false if string s does not contain at least one character.
529
(6) Returns false if string s does not contain at least one cased
531
(7) A titlecased string is a string in which uppercase characters may only
532
follow uncased characters and lowercase characters only cased ones.
533
(8) s is returned if width is less than len(s).
534
(9) If the optional argument maxsplit is given, only the first maxsplit
535
occurrences are replaced.
536
(10) If sep is not specified or None, any whitespace string is a separator.
537
If maxsplit is given, at most maxsplit splits are done.
538
(11) Line breaks are not included in the resulting list unless keepends is
540
(12) table must be a string of length 256. All characters occurring in the
541
optional argument deletechars are removed prior to translation.
543
String formatting with the % operator
545
formatString % args--> evaluates to a string
547
* formatString uses C printf format codes : %, c, s, i, d, u, o, x, X, e, E,
548
f, g, G, r (details below).
549
* Width and precision may be a * to specify that an integer argument gives
550
the actual width or precision.
551
* The flag characters -, +, blank, # and 0 are understood. (details below)
552
* %s will convert any type argument to string (uses str() function)
553
* args may be a single arg or a tuple of args
555
'%s has %03d quote types.' % ('Python', 2) # => 'Python has 002 quote types.'
557
* Right-hand-side can also be a mapping:
559
a = '%(lang)s has %(c)03d quote types.' % {'c':2, 'lang':'Python}
560
(vars() function very handy to use on right-hand-side.)
564
d Signed integer decimal.
565
i Signed integer decimal.
568
x Unsigned hexadecimal (lowercase).
569
X Unsigned hexadecimal (uppercase).
570
e Floating point exponential format (lowercase).
571
E Floating point exponential format (uppercase).
572
f Floating point decimal format.
573
F Floating point decimal format.
574
g Same as "e" if exponent is greater than -4 or less than precision,
576
G Same as "E" if exponent is greater than -4 or less than precision,
578
c Single character (accepts integer or single character string).
579
r String (converts any python object using repr()).
580
s String (converts any python object using str()).
581
% No argument is converted, results in a "%" character in the result.
582
(The complete specification is %%.)
584
Conversion flag characters
586
# The value conversion will use the ``alternate form''.
587
0 The conversion will be zero padded.
588
- The converted value is left adjusted (overrides "-").
589
(a space) A blank should be left before a positive number (or empty
590
string) produced by a signed conversion.
591
+ A sign character ("+" or "-") will precede the conversion (overrides a
596
Created with built-in function open; may be created by other modules' functions
599
Operators on file objects
603
f.close() Close file f.
604
f.fileno() Get fileno (fd) for file f.
605
f.flush() Flush file f's internal buffer.
606
f.isatty() True if file f is connected to a tty-like dev, else False.
607
f.read([size]) Read at most size bytes from file f and return as a string
608
object. If size omitted, read to EOF.
609
f.readline() Read one entire line from file f.
610
f.readlines() Read until EOF with readline() and return list of lines read.
611
Set file f's position, like "stdio's fseek()".
612
f.seek(offset[, whence == 0 then use absolute indexing.
613
whence=0]) whence == 1 then offset relative to current pos.
614
whence == 2 then offset relative to file end.
615
f.tell() Return file f's current position (byte offset).
616
f.write(str) Write string to file f.
617
f.writelines(list Write list of strings to file f.
623
End-of-file hit when reading (may be raised many times, e.g. if f is a
626
Other I/O-related I/O operation failure.
628
OS system call failed.
633
-See manuals for more details -
636
+ Class instance objects
637
+ Type objects (see module: types)
638
+ File objects (see above)
642
o User-defined (written in Python):
643
# User-defined Function objects
644
# User-defined Method objects
645
o Built-in (written in C):
646
# Built-in Function objects
647
# Built-in Method objects
649
o Code objects (byte-compile executable Python code: bytecode)
650
o Frame objects (execution frames)
651
o Traceback objects (stack trace of an exception)
656
pass -- Null statement
657
del name[,name]* -- Unbind name(s) from object. Object will be indirectly
658
(and automatically) deleted only if no longer referenced.
659
print [>> fileobject,] [s1 [, s2 ]* [,]
660
-- Writes to sys.stdout, or to fileobject if supplied.
661
Puts spaces between arguments. Puts newline at end
662
unless statement ends with comma.
663
Print is not required when running interactively,
664
simply typing an expression will print its value,
665
unless the value is None.
666
exec x [in globals [,locals]]
667
-- Executes x in namespaces provided. Defaults
668
to current namespaces. x can be a string, file
669
object or a function object.
670
callable(value,... [id=value], [*args], [**kw])
671
-- Call function callable with parameters. Parameters can
672
be passed by name or be omitted if function
673
defines default values. E.g. if callable is defined as
674
"def callable(p1=1, p2=2)"
675
"callable()" <=> "callable(1, 2)"
676
"callable(10)" <=> "callable(10, 2)"
677
"callable(p2=99)" <=> "callable(1, 99)"
678
*args is a tuple of positional arguments.
679
**kw is a dictionary of keyword arguments.
684
Operator Result Notes
685
a = b Basic assignment - assign object b to label a (1)
686
a += b Roughly equivalent to a = a + b (2)
687
a -= b Roughly equivalent to a = a - b (2)
688
a *= b Roughly equivalent to a = a * b (2)
689
a /= b Roughly equivalent to a = a / b (2)
690
a %= b Roughly equivalent to a = a % b (2)
691
a **= b Roughly equivalent to a = a ** b (2)
692
a &= b Roughly equivalent to a = a & b (2)
693
a |= b Roughly equivalent to a = a | b (2)
694
a ^= b Roughly equivalent to a = a ^ b (2)
695
a >>= b Roughly equivalent to a = a >> b (2)
696
a <<= b Roughly equivalent to a = a << b (2)
699
(1) Can unpack tuples, lists, and strings.
700
first, second = a[0:2]; [f, s] = range(2); c1,c2,c3='abc'
701
Tip: x,y = y,x swaps x and y.
702
(2) Not exactly equivalent - a is evaluated only once. Also, where
703
possible, operation performed in-place - a is modified rather than
709
[elif condition: suite]*
710
[else: suite] -- usual if/else_if/else statement
711
while condition: suite
713
-- usual while statement. "else" suite is executed
714
after loop exits, unless the loop is exited with
716
for element in sequence: suite
718
-- iterates over sequence, assigning each element to element.
719
Use built-in range function to iterate a number of times.
720
"else" suite executed at end unless loop exited
722
break -- immediately exits "for" or "while" loop
723
continue -- immediately does next iteration of "for" or "while" loop
724
return [result] -- Exits from function (or method) and returns result (use a tuple to
725
return more than one value). If no result given, then returns None.
726
yield result -- Freezes the execution frame of a generator and returns the result
727
to the iterator's .next() method. Upon the next call to next(),
728
resumes execution at the frozen point with all of the local variables
733
assert expr[, message]
734
-- expr is evaluated. if false, raises exception AssertionError
735
with message. Inhibited if __debug__ is 0.
737
[except [exception [, value]: suite2]+
739
-- statements in suite1 are executed. If an exception occurs, look
740
in "except" clauses for matching <exception>. If matches or bare
741
"except" execute suite of that clause. If no exception happens
742
suite in "else" clause is executed after suite1.
743
If exception has a value, it is put in value.
744
exception can also be tuple of exceptions, e.g.
745
"except (KeyError, NameError), val: print val"
748
-- statements in suite1 are executed. If no
749
exception, execute suite2 (even if suite1 is
750
exited with a "return", "break" or "continue"
751
statement). If exception did occur, executes
752
suite2 and then immediately reraises exception.
753
raise exception [,value [, traceback]]
754
-- raises exception with optional value
755
value. Arg traceback specifies a traceback object to
756
use when printing the exception's backtrace.
757
raise -- a raise statement without arguments re-raises
758
the last exception raised in the current function
759
An exception is either a string (object) or a class instance.
760
Can create a new one simply by creating a new string:
762
my_exception = 'You did something wrong'
765
raise my_exception, bad
766
except my_exception, value:
769
Exception classes must be derived from the predefined class: Exception, e.g.:
770
class text_exception(Exception): pass
773
raise text_exception()
774
# This is a shorthand for the form
775
# "raise <class>, <instance>"
778
# This will be printed because
779
# text_exception is a subclass of Exception
780
When an error message is printed for an unhandled exception which is a
781
class, the class name is printed, then a colon and a space, and
782
finally the instance converted to a string using the built-in function
784
All built-in exception classes derives from StandardError, itself
785
derived from Exception.
787
Name Space Statements
789
[1.51: On Mac & Windows, the case of module file names must now match the case
791
in the import statement]
792
Packages (>1.5): a package is a name space which maps to a directory including
793
module(s) and the special initialization module '__init__.py'
794
(possibly empty). Packages/dirs can be nested. You address a
795
module's symbol via '[package.[package...]module.symbol's.
796
import module1 [as name1] [, module2]*
797
-- imports modules. Members of module must be
798
referred to by qualifying with [package.]module name:
799
"import sys; print sys.argv:"
800
"import package1.subpackage.module; package1.subpackage.module.foo()"
801
module1 renamed as name1, if supplied.
802
from module import name1 [as othername1] [, name2]*
803
-- imports names from module module in current namespace.
804
"from sys import argv; print argv"
805
"from package1 import module; module.foo()"
806
"from package1.module import foo; foo()"
807
name1 renamed as othername1, if supplied.
809
-- imports all names in module, except those starting with "_";
810
*to be used sparsely, beware of name clashes* :
811
"from sys import *; print argv"
812
"from package.module import *; print x'
813
NB: "from package import *" only imports the symbols defined
814
in the package's __init__.py file, not those in the
816
global name1 [, name2]*
817
-- names are from global scope (usually meaning from module)
818
rather than local (usually meaning only in function).
819
-- E.g. in fct without "global" statements, assuming
820
"a" is name that hasn't been used in fct or module
822
-Try to read from "a" -> NameError
823
-Try to write to "a" -> creates "a" local to fcn
824
-If "a" not defined in fct, but is in module, then
825
-Try to read from "a", gets value from module
826
-Try to write to "a", creates "a" local to fct
827
But note "a[0]=3" starts with search for "a",
828
will use to global "a" if no local "a".
832
def func_id ([param_list]): suite
833
-- Creates a function object & binds it to name func_id.
835
param_list ::= [id [, id]*]
836
id ::= value | id = value | *id | **id
837
[Args are passed by value.Thus only args representing a mutable object
838
can be modified (are inout parameters). Use a tuple to return more than
842
def test (p1, p2 = 1+1, *rest, **keywords):
843
-- Parameters with "=" have default value (v is
844
evaluated when function defined).
845
If list has "*id" then id is assigned a tuple of
846
all remaining args passed to function (like C vararg)
847
If list has "**id" then id is assigned a dictionary of
848
all extra arguments passed as keywords.
852
class <class_id> [(<super_class1> [,<super_class2>]*)]: <suite>
853
-- Creates a class object and assigns it name <class_id>
854
<suite> may contain local "defs" of class methods and
855
assignments to class attributes.
857
class my_class (class1, class_list[3]): ...
858
Creates a class object inheriting from both "class1" and whatever
859
class object "class_list[3]" evaluates to. Assigns new
860
class object to name "my_class".
861
- First arg to class methods is always instance object, called 'self'
863
- Special method __init__() is called when instance is created.
864
- Special method __del__() called when no more reference to object.
865
- Create instance by "calling" class object, possibly with arg
866
(thus instance=apply(aClassObject, args...) creates an instance!)
867
- In current implementation, can't subclass off built-in
868
classes. But can "wrap" them, see UserDict & UserList modules,
869
and see __getattr__() below.
872
def __init__(self, name): self.name = name
873
def print_name(self): print "I'm", self.name
874
def call_parent(self): c_parent.print_name(self)
878
instance.print_name()
880
Call parent's super class by accessing parent's method
881
directly and passing "self" explicitly (see "call_parent"
883
Many other special methods available for implementing
884
arithmetic operators, sequence, mapping indexing, etc.
886
Documentation Strings
888
Modules, classes and functions may be documented by placing a string literal by
889
itself as the first statement in the suite. The documentation can be retrieved
890
by getting the '__doc__' attribute from the module, class or function.
895
"A description of the constructor"
897
Then c.__doc__ == "A description of C".
898
Then c.__init__.__doc__ == "A description of the constructor".
902
lambda [param_list]: returnedExpr
903
-- Creates an anonymous function. returnedExpr must be
904
an expression, not a statement (e.g., not "if xx:...",
905
"print xxx", etc.) and thus can't contain newlines.
906
Used mostly for filter(), map(), reduce() functions, and GUI callbacks..
908
result = [expression for item1 in sequence1 [if condition1]
909
[for item2 in sequence2 ... for itemN in sequenceN]
913
for item1 in sequence1:
914
for item2 in sequence2:
916
for itemN in sequenceN:
917
if (condition1) and furthur conditions:
918
result.append(expression)
926
__import__(name[, Imports module within the given context (see lib ref for
927
globals[, locals[, more details)
929
abs(x) Return the absolute value of number x.
930
apply(f, args[, Calls func/method f with arguments args and optional
932
bool(x) Returns True when the argument x is true and False otherwise.
933
buffer(obj) Creates a buffer reference to an object.
934
callable(x) Returns True if x callable, else False.
935
chr(i) Returns one-character string whose ASCII code isinteger i
936
classmethod(f) Converts a function f, into a method with the class as the
937
first argument. Useful for creating alternative constructors.
938
cmp(x,y) Returns negative, 0, positive if x <, ==, > to y
939
coerce(x,y) Returns a tuple of the two numeric arguments converted to a
941
Compiles string into a code object.filename is used in
942
error message, can be any string. It isusually the file
943
compile(string, from which the code was read, or eg. '<string>'if not read
944
filename, kind) from file.kind can be 'eval' if string is a single stmt, or
945
'single' which prints the output of expression statements
946
thatevaluate to something else than None, or be 'exec'.
947
complex(real[, Builds a complex object (can also be done using J or j
948
image]) suffix,e.g. 1+3J)
949
delattr(obj, name) deletes attribute named name of object obj <=> del obj.name
950
If no args, returns the list of names in current
951
dict([items]) Create a new dictionary from the specified item list.
952
dir([object]) localsymbol table. With a module, class or class
953
instanceobject as arg, returns list of names in its attr.
955
divmod(a,b) Returns tuple of (a/b, a%b)
956
enumerate(seq) Return a iterator giving: (0, seq[0]), (1, seq[1]), ...
957
eval(s[, globals[, Eval string s in (optional) globals, locals contexts.s must
958
locals]]) have no NUL's or newlines. s can also be acode object.
959
Example: x = 1; incr_x = eval('x + 1')
960
execfile(file[, Executes a file without creating a new module, unlike
961
globals[, locals]]) import.
962
file() Synonym for open().
963
filter(function, Constructs a list from those elements of sequence for which
964
sequence) function returns true. function takes one parameter.
965
float(x) Converts a number or a string to floating point.
966
getattr(object, [<default> arg added in 1.5.2]Gets attribute called name
967
name[, default])) from object,e.g. getattr(x, 'f') <=> x.f). If not found,
968
raisesAttributeError or returns default if specified.
969
globals() Returns a dictionary containing current global variables.
970
hasattr(object, Returns true if object has attr called name.
972
hash(object) Returns the hash value of the object (if it has one)
973
help(f) Display documentation on object f.
974
hex(x) Converts a number x to a hexadecimal string.
975
id(object) Returns a unique 'identity' integer for an object.
976
input([prompt]) Prints prompt if given. Reads input and evaluates it.
977
Converts a number or a string to a plain integer. Optional
978
int(x[, base]) base paramenter specifies base from which to convert string
980
intern(aString) Enters aString in the table of "interned strings"
981
andreturns the string. Interned strings are 'immortals'.
982
isinstance(obj, returns true if obj is an instance of class. Ifissubclass
983
class) (A,B) then isinstance(x,A) => isinstance(x,B)
984
issubclass(class1, returns true if class1 is derived from class2
986
Returns the length (the number of items) of an object
987
iter(collection) Returns an iterator over the collection.
988
len(obj) (sequence, dictionary, or instance of class implementing
990
list(sequence) Converts sequence into a list. If already a list,returns a
992
locals() Returns a dictionary containing current local variables.
993
Converts a number or a string to a long integer. Optional
994
long(x[, base]) base paramenter specifies base from which to convert string
996
Applies function to every item of list and returns a listof
997
map(function, list, the results. If additional arguments are passed,function
998
...) must take that many arguments and it is givento function on
1000
max(seq) Returns the largest item of the non-empty sequence seq.
1001
min(seq) Returns the smallest item of a non-empty sequence seq.
1002
oct(x) Converts a number to an octal string.
1003
open(filename [, Returns a new file object. First two args are same asthose
1004
mode='r', [bufsize= for C's "stdio open" function. bufsize is 0for unbuffered,
1005
implementation 1 for line-buffered, negative forsys-default, all else, of
1006
dependent]]) (about) given size.
1007
ord(c) Returns integer ASCII value of c (a string of len 1). Works
1009
object() Create a base type. Used as a superclass for new-style objects.
1010
open(name Open a file.
1013
pow(x, y [, z]) Returns x to power y [modulo z]. See also ** operator.
1014
property() Created a property with access controlled by functions.
1015
range(start [,end Returns list of ints from >= start and < end.With 1 arg,
1016
[, step]]) list from 0..arg-1With 2 args, list from start..end-1With 3
1017
args, list from start up to end by step
1018
raw_input([prompt]) Prints prompt if given, then reads string from stdinput (no
1019
trailing \n). See also input().
1020
reduce(f, list [, Applies the binary function f to the items oflist so as to
1021
init]) reduce the list to a single value.If init given, it is
1022
"prepended" to list.
1023
Re-parses and re-initializes an already imported module.
1024
Useful in interactive mode, if you want to reload amodule
1025
reload(module) after fixing it. If module was syntacticallycorrect but had
1026
an error in initialization, mustimport it one more time
1027
before calling reload().
1028
Returns a string containing a printable and if possible
1029
repr(object) evaluable representation of an object. <=> `object`
1030
(usingbackquotes). Class redefinissable (__repr__). See
1032
round(x, n=0) Returns the floating point value x rounded to n digitsafter
1034
setattr(object, This is the counterpart of getattr().setattr(o, 'foobar',
1035
name, value) 3) <=> o.foobar = 3Creates attribute if it doesn't exist!
1036
slice([start,] stop Returns a slice object representing a range, with R/
1037
[, step]) Oattributes: start, stop, step.
1038
Returns a string containing a nicely
1039
staticmethod() Convert a function to method with no self or class
1040
argument. Useful for methods associated with a class that
1041
do not need access to an object's internal state.
1042
str(object) printablerepresentation of an object. Class overridable
1043
(__str__).See also repr().
1044
super(type) Create an unbound super object. Used to call cooperative
1046
sum(sequence, Add the values in the sequence and return the sum.
1048
tuple(sequence) Creates a tuple with same elements as sequence. If already
1049
a tuple, return itself (not a copy).
1050
Returns a type object [see module types] representing
1051
thetype of obj. Example: import typesif type(x) ==
1052
type(obj) types.StringType: print 'It is a string'NB: it is
1053
recommanded to use the following form:if isinstance(x,
1054
types.StringType): etc...
1056
unicode(string[, Creates a Unicode string from a 8-bit string, using
1057
encoding[, error thegiven encoding name and error treatment ('strict',
1058
]]]) 'ignore',or 'replace'}.
1059
Without arguments, returns a dictionary correspondingto the
1060
current local symbol table. With a module,class or class
1061
vars([object]) instance object as argumentreturns a dictionary
1062
corresponding to the object'ssymbol table. Useful with "%"
1063
formatting operator.
1064
xrange(start [, end Like range(), but doesn't actually store entire listall at
1065
[, step]]) once. Good to use in "for" loops when there is abig range
1067
zip(seq1[, seq2, Returns a list of tuples where each tuple contains the nth
1068
...]) element of each of the argument sequences.
1076
Root class for all exceptions
1080
Signal the end from iterator.next()
1082
Base class for all built-in exceptions; derived from Exception
1085
Base class for OverflowError, ZeroDivisionError,
1088
When a floating point operation fails.
1090
On excessively large arithmetic operation
1092
On division or modulo operation with 0 as 2nd arg
1094
When an assert statement fails.
1096
On attribute reference or assignment failure
1097
EnvironmentError [new in 1.5.2]
1098
On error outside Python; error arg tuple is (errno, errMsg...)
1099
IOError [changed in 1.5.2]
1100
I/O-related operation failure
1101
OSError [new in 1.5.2]
1102
used by the os module's os.error exception.
1104
Immediate end-of-file hit by input() or raw_input()
1106
On failure of `import' to find module or name
1108
On user entry of the interrupt key (often `Control-C')
1110
base class for IndexError, KeyError
1112
On out-of-range sequence subscript
1114
On reference to a non-existent mapping (dict) key
1116
On recoverable memory exhaustion
1118
On failure to find a local or global (unqualified) name
1120
Obsolete catch-all; define a suitable error instead
1121
NotImplementedError [new in 1.5.2]
1122
On method not implemented
1124
On parser encountering a syntax error
1126
On parser encountering an indentation syntax error
1128
On parser encountering an indentation syntax error
1130
On non-fatal interpreter error - bug - report it
1132
On passing inappropriate type to built-in op or func
1134
On arg error not covered by TypeError or more precise
1138
PendingDeprecationWarning
1145
Standard methods & operators redefinition in classes
1147
Standard methods & operators map to special '__methods__' and thus may be
1148
redefined (mostly in in user-defined classes), e.g.:
1150
def __init__(self, v): self.value = v
1151
def __add__(self, r): return self.value + r
1152
a = x(3) # sort of like calling x.__init__(a, 3)
1153
a + 4 # is equivalent to a.__add__(4)
1155
Special methods for any class
1158
__init__(s, args) instance initialization (on construction)
1159
__del__(s) called on object demise (refcount becomes 0)
1160
__repr__(s) repr() and `...` conversions
1161
__str__(s) str() and 'print' statement
1162
__cmp__(s, o) Compares s to o and returns <0, 0, or >0.
1163
Implements >, <, == etc...
1164
__hash__(s) Compute a 32 bit hash code; hash() and dictionary ops
1165
__nonzero__(s) Returns False or True for truth value testing
1166
__getattr__(s, name) called when attr lookup doesn't find <name>
1167
__setattr__(s, name, val) called when setting an attr
1168
(inside, don't use "self.name = value"
1169
use "self.__dict__[name] = val")
1170
__delattr__(s, name) called to delete attr <name>
1171
__call__(self, *args) called when an instance is called as function.
1175
See list in the operator module. Operator function names are provided with
1176
2 variants, with or without
1177
ading & trailing '__' (eg. __add__ or add).
1179
Numeric operations special methods
1182
s+o = __add__(s,o) s-o = __sub__(s,o)
1183
s*o = __mul__(s,o) s/o = __div__(s,o)
1184
s%o = __mod__(s,o) divmod(s,o) = __divmod__(s,o)
1187
s^o = __xor__(s,o) s|o = __or__(s,o)
1188
s<<o = __lshift__(s,o) s>>o = __rshift__(s,o)
1189
nonzero(s) = __nonzero__(s) (used in boolean testing)
1190
-s = __neg__(s) +s = __pos__(s)
1191
abs(s) = __abs__(s) ~s = __invert__(s) (bitwise)
1192
s+=o = __iadd__(s,o) s-=o = __isub__(s,o)
1193
s*=o = __imul__(s,o) s/=o = __idiv__(s,o)
1194
s%=o = __imod__(s,o)
1195
s**=o = __ipow__(s,o)
1196
s&=o = __iand__(s,o)
1197
s^=o = __ixor__(s,o) s|=o = __ior__(s,o)
1198
s<<=o = __ilshift__(s,o) s>>=o = __irshift__(s,o)
1200
int(s) = __int__(s) long(s) = __long__(s)
1201
float(s) = __float__(s) complex(s) = __complex__(s)
1202
oct(s) = __oct__(s) hex(s) = __hex__(s)
1203
coerce(s,o) = __coerce__(s,o)
1204
Right-hand-side equivalents for all binary operators exist;
1205
are called when class instance is on r-h-s of operator:
1206
a + 3 calls __add__(a, 3)
1207
3 + a calls __radd__(a, 3)
1209
All seqs and maps, general operations plus:
1210
(s: self, i: index or key)
1212
len(s) = __len__(s) length of object, >= 0. Length 0 == false
1213
s[i] = __getitem__(s,i) Element at index/key i, origin 0
1215
Sequences, general methods, plus:
1216
s[i]=v = __setitem__(s,i,v)
1217
del s[i] = __delitem__(s,i)
1218
s[i:j] = __getslice__(s,i,j)
1219
s[i:j]=seq = __setslice__(s,i,j,seq)
1220
del s[i:j] = __delslice__(s,i,j) == s[i:j] = []
1221
seq * n = __repeat__(seq, n)
1222
s1 + s2 = __concat__(s1, s2)
1223
i in s = __contains__(s, i)
1224
Mappings, general methods, plus
1225
hash(s) = __hash__(s) - hash value for dictionary references
1226
s[k]=v = __setitem__(s,k,v)
1227
del s[k] = __delitem__(s,k)
1229
Special informative state attributes for some types:
1232
__doc__ (string/None, R/O): doc string (<=> __dict__['__doc__'])
1233
__name__(string, R/O): module name (also in __dict__['__name__'])
1234
__dict__ (dict, R/O): module's name space
1235
__file__(string/undefined, R/O): pathname of .pyc, .pyo or .pyd (undef for
1236
modules statically linked to the interpreter)
1238
Classes: [in bold: writable since 1.5.2]
1239
__doc__ (string/None, R/W): doc string (<=> __dict__['__doc__'])
1240
__module__ is the module name in which the class was defined
1241
__name__(string, R/W): class name (also in __dict__['__name__'])
1242
__bases__ (tuple, R/W): parent classes
1243
__dict__ (dict, R/W): attributes (class name space)
1246
__class__ (class, R/W): instance's class
1247
__dict__ (dict, R/W): attributes
1249
User-defined functions: [bold: writable since 1.5.2]
1250
__doc__ (string/None, R/W): doc string
1251
__name__(string, R/O): function name
1252
func_doc (R/W): same as __doc__
1253
func_name (R/O): same as __name__
1254
func_defaults (tuple/None, R/W): default args values if any
1255
func_code (code, R/W): code object representing the compiled function body
1256
func_globals (dict, R/O): ref to dictionary of func global variables
1257
func_dict (dict, R/W): same as __dict__ contains the namespace supporting
1258
arbitrary function attributes
1259
func_closure (R/O): None or a tuple of cells that contain bindings
1260
for the function's free variables.
1263
User-defined Methods:
1264
__doc__ (string/None, R/O): doc string
1265
__name__(string, R/O): method name (same as im_func.__name__)
1266
im_class (class, R/O): class defining the method (may be a base class)
1267
im_self (instance/None, R/O): target instance object (None if unbound)
1268
im_func (function, R/O): function object
1270
Built-in Functions & methods:
1271
__doc__ (string/None, R/O): doc string
1272
__name__ (string, R/O): function name
1273
__self__ : [methods only] target object
1276
co_name (string, R/O): function name
1277
co_argcount (int, R/0): number of positional args
1278
co_nlocals (int, R/O): number of local vars (including args)
1279
co_varnames (tuple, R/O): names of local vars (starting with args)
1280
co_cellvars (tuple, R/O)) the names of local variables referenced by
1282
co_freevars (tuple, R/O)) names of free variables
1283
co_code (string, R/O): sequence of bytecode instructions
1284
co_consts (tuple, R/O): litterals used by the bytecode, 1st one is
1286
co_names (tuple, R/O): names used by the bytecode
1287
co_filename (string, R/O): filename from which the code was compiled
1288
co_firstlineno (int, R/O): first line number of the function
1289
co_lnotab (string, R/O): string encoding bytecode offsets to line numbers.
1290
co_stacksize (int, R/O): required stack size (including local vars)
1291
co_flags (int, R/O): flags for the interpreter
1292
bit 2 set if fct uses "*arg" syntax
1293
bit 3 set if fct uses '**keywords' syntax
1295
f_back (frame/None, R/O): previous stack frame (toward the caller)
1296
f_code (code, R/O): code object being executed in this frame
1297
f_locals (dict, R/O): local vars
1298
f_globals (dict, R/O): global vars
1299
f_builtins (dict, R/O): built-in (intrinsic) names
1300
f_restricted (int, R/O): flag indicating whether fct is executed in
1302
f_lineno (int, R/O): current line number
1303
f_lasti (int, R/O): precise instruction (index into bytecode)
1304
f_trace (function/None, R/W): debug hook called at start of each source line
1305
f_exc_type (Type/None, R/W): Most recent exception type
1306
f_exc_value (any, R/W): Most recent exception value
1307
f_exc_traceback (traceback/None, R/W): Most recent exception traceback
1309
tb_next (frame/None, R/O): next level in stack trace (toward the frame where
1310
the exception occurred)
1311
tb_frame (frame, R/O): execution frame of the current level
1312
tb_lineno (int, R/O): line number where the exception occurred
1313
tb_lasti (int, R/O): precise instruction (index into bytecode)
1316
start (any/None, R/O): lowerbound
1317
stop (any/None, R/O): upperbound
1318
step (any/None, R/O): step value
1321
real (float, R/O): real part
1322
imag (float, R/O): imaginary part
1331
argv The list of command line arguments passed to aPython
1332
script. sys.argv[0] is the script name.
1333
builtin_module_names A list of strings giving the names of all moduleswritten
1334
in C that are linked into this interpreter.
1335
check_interval How often to check for thread switches or signals(measured
1336
in number of virtual machine instructions)
1337
exc_type, exc_value, Deprecated since release 1.5. Use exc_info() instead.
1339
exitfunc User can set to a parameterless fcn. It will getcalled
1340
before interpreter exits.
1341
last_type, Set only when an exception not handled andinterpreter
1342
last_value, prints an error. Used by debuggers.
1344
maxint maximum positive value for integers
1345
modules Dictionary of modules that have already been loaded.
1346
path Search path for external modules. Can be modifiedby
1347
program. sys.path[0] == dir of script executing
1348
platform The current platform, e.g. "sunos5", "win32"
1349
ps1, ps2 prompts to use in interactive mode.
1350
File objects used for I/O. One can redirect byassigning a
1351
stdin, stdout, new file object to them (or any object:.with a method
1352
stderr write(string) for stdout/stderr,.with a method readline()
1354
version string containing version info about Python interpreter.
1355
(and also: copyright, dllhandle, exec_prefix, prefix)
1356
version_info tuple containing Python version info - (major, minor,
1357
micro, level, serial).
1361
exit(n) Exits with status n. Raises SystemExit exception.(Hence can
1362
be caught and ignored by program)
1363
getrefcount(object Returns the reference count of the object. Generally one
1364
) higher than you might expect, because of object arg temp
1366
setcheckinterval( Sets the interpreter's thread switching interval (in number
1367
interval) of virtual code instructions, default:100).
1368
settrace(func) Sets a trace function: called before each line ofcode is
1370
setprofile(func) Sets a profile function for performance profiling.
1371
Info on exception currently being handled; this is atuple
1372
(exc_type, exc_value, exc_traceback).Warning: assigning the
1373
exc_info() traceback return value to a local variable in a
1374
function handling an exception will cause a circular
1376
setdefaultencoding Change default Unicode encoding - defaults to 7-bit ASCII.
1378
getrecursionlimit Retrieve maximum recursion depth.
1380
setrecursionlimit Set maximum recursion depth. (Defaults to 1000.)
1386
"synonym" for whatever O/S-specific module is proper for current environment.
1387
this module uses posix whenever possible.
1388
(see also M.A. Lemburg's utility http://www.lemburg.com/files/python/
1393
name name of O/S-specific module (e.g. "posix", "mac", "nt")
1394
path O/S-specific module for path manipulations.
1395
On Unix, os.path.split() <=> posixpath.split()
1396
curdir string used to represent current directory ('.')
1397
pardir string used to represent parent directory ('..')
1398
sep string used to separate directories ('/' or '\'). Tip: use
1399
os.path.join() to build portable paths.
1400
altsep Alternate sep
1403
pathsep character used to separate search path components (as in
1404
$PATH), eg. ';' for windows.
1405
linesep line separator as used in binary files, ie '\n' on Unix, '\
1406
r\n' on Dos/Win, '\r'
1410
makedirs(path[, Recursive directory creation (create required intermediary
1411
mode=0777]) dirs); os.error if fails.
1412
removedirs(path) Recursive directory delete (delete intermediary empty
1414
renames(old, new) Recursive directory or file renaming; os.error if fails.
1419
don't import this module directly, import os instead !
1420
(see also module: shutil for file copy & remove fcts)
1424
environ dictionary of environment variables, e.g.posix.environ['HOME'].
1425
error exception raised on POSIX-related error.
1426
Corresponding value is tuple of errno code and perror() string.
1428
Some posix functions
1430
chdir(path) Changes current directory to path.
1431
chmod(path, Changes the mode of path to the numeric mode
1433
close(fd) Closes file descriptor fd opened with posix.open.
1434
_exit(n) Immediate exit, with no cleanups, no SystemExit,etc. Should use
1435
this to exit a child process.
1436
execv(p, args) "Become" executable p with args args
1437
getcwd() Returns a string representing the current working directory
1438
getpid() Returns the current process id
1439
fork() Like C's fork(). Returns 0 to child, child pid to parent.[Not
1441
kill(pid, Like C's kill [Not on Windows]
1443
listdir(path) Lists (base)names of entries in directory path, excluding '.'
1445
lseek(fd, pos, Sets current position in file fd to position pos, expressedas
1446
how) an offset relative to beginning of file (how=0), tocurrent
1447
position (how=1), or to end of file (how=2)
1448
mkdir(path[, Creates a directory named path with numeric mode (default 0777)
1450
open(file, Like C's open(). Returns file descriptor. Use file object
1451
flags, mode) fctsrather than this low level ones.
1452
pipe() Creates a pipe. Returns pair of file descriptors (r, w) [Not on
1454
popen(command, Opens a pipe to or from command. Result is a file object to
1455
mode='r', read to orwrite from, as indicated by mode being 'r' or 'w'.
1456
bufSize=0) Use it to catch acommand output ('r' mode) or to feed it ('w'
1458
remove(path) See unlink.
1459
rename(src, dst Renames/moves the file or directory src to dst. [error iftarget
1460
) name already exists]
1461
rmdir(path) Removes the empty directory path
1462
read(fd, n) Reads n bytes from file descriptor fd and return as string.
1463
Returns st_mode, st_ino, st_dev, st_nlink, st_uid,st_gid,
1464
stat(path) st_size, st_atime, st_mtime, st_ctime.[st_ino, st_uid, st_gid
1465
are dummy on Windows]
1466
system(command) Executes string command in a subshell. Returns exitstatus of
1467
subshell (usually 0 means OK).
1468
Returns accumulated CPU times in sec (user, system, children's
1469
times() user,children's sys, elapsed real time). [3 last not on
1471
unlink(path) Unlinks ("deletes") the file (not dir!) path. same as: remove
1472
utime(path, ( Sets the access & modified time of the file to the given tuple
1473
aTime, mTime)) of values.
1474
wait() Waits for child process completion. Returns tuple ofpid,
1475
exit_status [Not on Windows]
1476
waitpid(pid, Waits for process pid to complete. Returns tuple ofpid,
1477
options) exit_status [Not on Windows]
1478
write(fd, str) Writes str to file fd. Returns nb of bytes written.
1483
Do not import this module directly, import os instead and refer to this module
1484
as os.path. (e.g. os.path.exists(p)) !
1486
Some posixpath functions
1488
abspath(p) Returns absolute path for path p, taking current working dir in
1491
basename(p directory and name parts of the path p. See also split.
1493
exists(p) True if string p is an existing path (file or directory)
1494
expanduser Returns string that is (a copy of) p with "~" expansion done.
1496
expandvars Returns string that is (a copy of) p with environment vars expanded.
1497
(p) [Windows: case significant; must use Unix: $var notation, not %var%]
1498
getsize( return the size in bytes of filename. raise os.error.
1500
getmtime( return last modification time of filename (integer nb of seconds
1501
filename) since epoch).
1502
getatime( return last access time of filename (integer nb of seconds since
1504
isabs(p) True if string p is an absolute path.
1505
isdir(p) True if string p is a directory.
1506
islink(p) True if string p is a symbolic link.
1507
ismount(p) True if string p is a mount point [true for all dirs on Windows].
1508
join(p[,q Joins one or more path components intelligently.
1510
Splits p into (head, tail) where tail is lastpathname component and
1511
split(p) <head> is everything leadingup to that. <=> (dirname(p), basename
1513
splitdrive Splits path p in a pair ('drive:', tail) [Windows]
1515
splitext(p Splits into (root, ext) where last comp of root contains no periods
1516
) and ext is empty or startswith a period.
1517
Calls the function visit with arguments(arg, dirname, names) for
1518
each directory recursively inthe directory tree rooted at p
1519
walk(p, (including p itself if it's a dir)The argument dirname specifies the
1520
visit, arg visited directory, the argumentnames lists the files in the
1521
) directory. The visit function maymodify names to influence the set
1522
of directories visited belowdirname, e.g., to avoid visiting certain
1528
high-level file operations (copying, deleting).
1530
Main shutil functions
1532
copy(src, dst) Copies the contents of file src to file dst, retaining file
1534
copytree(src, dst Recursively copies an entire directory tree rooted at src
1535
[, symlinks]) into dst (which should not already exist). If symlinks is
1536
true, links insrc are kept as such in dst.
1537
rmtree(path[, Deletes an entire directory tree, ignoring errors if
1538
ignore_errors[, ignore_errors true,or calling onerror(func, path,
1539
onerror]]) sys.exc_info()) if supplied with
1541
(and also: copyfile, copymode, copystat, copy2)
1547
altzone signed offset of local DST timezone in sec west of the 0th meridian.
1548
daylight nonzero if a DST timezone is specified
1552
time() return a float representing UTC time in seconds since the epoch.
1553
gmtime(secs), return a tuple representing time : (year aaaa, month(1-12),day
1554
localtime( (1-31), hour(0-23), minute(0-59), second(0-59), weekday(0-6, 0 is
1555
secs) monday), Julian day(1-366), daylight flag(-1,0 or 1))
1559
format, return a formated string representing time.
1561
mktime(tuple) inverse of localtime(). Return a float.
1562
strptime( parse a formated string representing time, return tuple as in
1565
sleep(secs) Suspend execution for <secs> seconds. <secs> can be a float.
1567
and also: clock, ctime.
1571
As of Python 2.0, much (though not all) of the functionality provided by the
1572
string module have been superseded by built-in string methods - see Operations
1573
on strings for details.
1575
Some string variables
1577
digits The string '0123456789'
1578
hexdigits, octdigits legal hexadecimal & octal digits
1579
letters, uppercase, lowercase, Strings containing the appropriate
1580
whitespace characters
1581
index_error Exception raised by index() if substr not
1584
Some string functions
1586
expandtabs(s, returns a copy of string <s> with tabs expanded.
1588
find/rfind(s, sub Return the lowest/highest index in <s> where the substring
1589
[, start=0[, end= <sub> is found such that <sub> is wholly contained ins
1590
0]) [start:end]. Return -1 if <sub> not found.
1591
ljust/rjust/center Return a copy of string <s> left/right justified/centerd in
1592
(s, width) afield of given width, padded with spaces. <s> is
1594
lower/upper(s) Return a string that is (a copy of) <s> in lowercase/
1596
split(s[, sep= Return a list containing the words of the string <s>,using
1597
whitespace[, the string <sep> as a separator.
1599
join(words[, sep=' Concatenate a list or tuple of words with
1600
']) interveningseparators; inverse of split.
1601
replace(s, old, Returns a copy of string <s> with all occurrences of
1602
new[, maxsplit=0] substring<old> replaced by <new>. Limits to <maxsplit>
1603
firstsubstitutions if specified.
1604
strip(s) Return a string that is (a copy of) <s> without leadingand
1605
trailing whitespace. see also lstrip, rstrip.
1611
Handles Unicode strings. Implemented in new module sre, re now a mere front-end
1613
Patterns are specified as strings. Tip: Use raw strings (e.g. r'\w*') to
1614
litteralize backslashes.
1617
Regular expression syntax
1619
. matches any character (including newline if DOTALL flag specified)
1620
^ matches start of the string (of every line in MULTILINE mode)
1621
$ matches end of the string (of every line in MULTILINE mode)
1622
* 0 or more of preceding regular expression (as many as possible)
1623
+ 1 or more of preceding regular expression (as many as possible)
1624
? 0 or 1 occurrence of preceding regular expression
1625
*?, +?, ?? Same as *, + and ? but matches as few characters as possible
1626
{m,n} matches from m to n repetitions of preceding RE
1627
{m,n}? idem, attempting to match as few repetitions as possible
1628
[ ] defines character set: e.g. '[a-zA-Z]' to match all letters(see also
1630
[^ ] defines complemented character set: matches if char is NOT in set
1631
escapes special chars '*?+&$|()' and introduces special sequences
1632
\ (see below). Due to Python string rules, write as '\\' orr'\' in the
1634
\\ matches a litteral '\'; due to Python string rules, write as '\\\\
1635
'in pattern string, or better using raw string: r'\\'.
1636
| specifies alternative: 'foo|bar' matches 'foo' or 'bar'
1637
(...) matches any RE inside (), and delimits a group.
1638
(?:...) idem but doesn't delimit a group.
1639
matches if ... matches next, but doesn't consume any of the string
1640
(?=...) e.g. 'Isaac (?=Asimov)' matches 'Isaac' only if followed by
1642
(?!...) matches if ... doesn't match next. Negative of (?=...)
1643
(?P<name matches any RE inside (), and delimits a named group. (e.g. r'(?P
1644
>...) <id>[a-zA-Z_]\w*)' defines a group named id)
1645
(?P=name) matches whatever text was matched by the earlier group named name.
1646
(?#...) A comment; ignored.
1647
(?letter) letter is one of 'i','L', 'm', 's', 'x'. Set the corresponding flags
1648
(re.I, re.L, re.M, re.S, re.X) for the entire RE.
1651
Sequence Description
1652
number matches content of the group of the same number; groups are numbered
1654
\A matches only at the start of the string
1655
\b empty str at beg or end of word: '\bis\b' matches 'is', but not 'his'
1656
\B empty str NOT at beginning or end of word
1657
\d any decimal digit (<=> [0-9])
1658
\D any non-decimal digit char (<=> [^O-9])
1659
\s any whitespace char (<=> [ \t\n\r\f\v])
1660
\S any non-whitespace char (<=> [^ \t\n\r\f\v])
1661
\w any alphaNumeric char (depends on LOCALE flag)
1662
\W any non-alphaNumeric char (depends on LOCALE flag)
1663
\Z matches only at the end of the string
1667
error Exception when pattern string isn't a valid regexp.
1671
Compile a RE pattern string into a regular expression object.
1672
Flags (combinable by |):
1674
I or IGNORECASE or (?i)
1675
case insensitive matching
1676
compile( L or LOCALE or (?L)
1677
pattern[, make \w, \W, \b, \B dependent on thecurrent locale
1678
flags=0]) M or MULTILINE or (?m)
1679
matches every new line and not onlystart/end of the whole
1682
'.' matches ALL chars, including newline
1683
X or VERBOSE or (?x)
1684
Ignores whitespace outside character sets
1685
escape(string) return (a copy of) string with all non-alphanumerics
1687
match(pattern, if 0 or more chars at beginning of <string> match the RE pattern
1688
string[, flags string,return a corresponding MatchObject instance, or None if
1690
search(pattern scan thru <string> for a location matching <pattern>, return
1691
, string[, acorresponding MatchObject instance, or None if no match.
1693
split(pattern, split <string> by occurrences of <pattern>. If capturing () are
1694
string[, used inpattern, then occurrences of patterns or subpatterns are
1695
maxsplit=0]) also returned.
1696
findall( return a list of non-overlapping matches in <pattern>, either a
1697
pattern, list ofgroups or a list of tuples if the pattern has more than 1
1699
return string obtained by replacing the (<count> first) lefmost
1700
sub(pattern, non-overlapping occurrences of <pattern> (a string or a RE
1701
repl, string[, object) in <string>by <repl>; <repl> can be a string or a fct
1702
count=0]) called with a single MatchObj arg, which must return the
1705
repl, string[, same as sub(), but returns a tuple (newString, numberOfSubsMade)
1708
Regular Expression Objects
1711
(RE objects are returned by the compile fct)
1713
re object attributes
1714
Attribute Descrition
1715
flags flags arg used when RE obj was compiled, or 0 if none provided
1716
groupindex dictionary of {group name: group number} in pattern
1717
pattern pattern string from which RE obj was compiled
1721
If zero or more characters at the beginning of string match this
1722
regular expression, return a corresponding MatchObject instance.
1723
Return None if the string does not match the pattern; note that
1724
this is different from a zero-length match.
1725
The optional second parameter pos gives an index in the string
1726
match( where the search is to start; it defaults to 0. This is not
1727
string[, completely equivalent to slicing the string; the '' pattern
1728
pos][, character matches at the real beginning of the string and at
1729
endpos]) positions just after a newline, but not necessarily at the index
1730
where the search is to start.
1731
The optional parameter endpos limits how far the string will be
1732
searched; it will be as if the string is endpos characters long, so
1733
only the characters from pos to endpos will be searched for a
1735
Scan through string looking for a location where this regular
1736
search( expression produces a match, and return a corresponding MatchObject
1737
string[, instance. Return None if no position in the string matches the
1738
pos][, pattern; note that this is different from finding a zero-length
1739
endpos]) match at some point in the string.
1740
The optional pos and endpos parameters have the same meaning as for
1743
string[, Identical to the split() function, using the compiled pattern.
1746
findall( Identical to the findall() function, using the compiled pattern.
1749
string[, Identical to the sub() function, using the compiled pattern.
1752
string[, Identical to the subn() function, using the compiled pattern.
1758
(Match objects are returned by the match & search functions)
1760
Match object attributes
1761
Attribute Description
1762
pos value of pos passed to search or match functions; index intostring at
1763
which RE engine started search.
1764
endpos value of endpos passed to search or match functions; index intostring
1765
beyond which RE engine won't go.
1766
re RE object whose match or search fct produced this MatchObj instance
1767
string string passed to match() or search()
1769
Match object functions
1771
returns one or more groups of the match. If one arg, result is a
1772
group([g1 string;if multiple args, result is a tuple with one item per arg. If
1773
, g2, gi is 0,return value is entire matching string; if 1 <= gi <= 99,
1774
...]) returnstring matching group #gi (or None if no such group); gi may
1775
also bea group name.
1776
returns a tuple of all groups of the match; groups not
1777
groups() participatingto the match have a value of None. Returns a string
1778
instead of tupleif len(tuple)=1
1780
group), returns indices of start & end of substring matched by group (or
1781
end(group Noneif group exists but doesn't contribute to the match)
1783
span( returns the 2-tuple (start(group), end(group)); can be (None, None)if
1784
group) group didn't contibute to the match.
1793
Functions (see ordinary C man pages for info):
1806
frexp(x) -- Unlike C: (float, int) = frexp(float)
1810
modf(x) -- Unlike C: (float, float) = modf(float)
1822
getopt(list, optstr) -- Similar to C. <optstr> is option
1823
letters to look for. Put ':' after letter
1824
if option takes arg. E.g.
1825
# invocation was "python test.py -c hi -a arg1 arg2"
1826
opts, args = getopt.getopt(sys.argv[1:], 'ab:c:')
1828
[('-c', 'hi'), ('-a', '')]
1833
List of modules and packages in base distribution
1835
(built-ins and content of python Lib directory)
1836
(Python NT distribution, may be slightly different in other distributions)
1838
Standard library modules
1840
aifc Stuff to parse AIFF-C and AIFF files.
1841
anydbm Generic interface to all dbm clones. (dbhash, gdbm,
1843
asynchat Support for 'chat' style protocols
1844
asyncore Asynchronous File I/O (in select style)
1845
atexit Register functions to be called at exit of Python interpreter.
1846
audiodev Audio support for a few platforms.
1847
base64 Conversions to/from base64 RFC-MIME transport encoding .
1848
BaseHTTPServer Base class forhttp services.
1849
Bastion "Bastionification" utility (control access to instance vars)
1850
bdb A generic Python debugger base class.
1851
binhex Macintosh binhex compression/decompression.
1852
bisect List bisection algorithms.
1853
bz2 Support for bz2 compression/decompression.
1854
calendar Calendar printing functions.
1855
cgi Wraps the WWW Forms Common Gateway Interface (CGI).
1856
cgitb Utility for handling CGI tracebacks.
1857
CGIHTTPServer CGI http services.
1858
cmd A generic class to build line-oriented command interpreters.
1859
datetime Basic date and time types.
1860
code Utilities needed to emulate Python's interactive interpreter
1861
codecs Lookup existing Unicode encodings and register new ones.
1862
colorsys Conversion functions between RGB and other color systems.
1863
commands Tools for executing UNIX commands .
1864
compileall Force "compilation" of all .py files in a directory.
1865
ConfigParser Configuration file parser (much like windows .ini files)
1866
copy Generic shallow and deep copying operations.
1867
copy_reg Helper to provide extensibility for pickle/cPickle.
1868
csv Read and write files with comma separated values.
1869
dbhash (g)dbm-compatible interface to bsdhash.hashopen.
1870
dircache Sorted list of files in a dir, using a cache.
1871
[DEL:dircmp:DEL] [DEL:Defines a class to build directory diff tools on.:DEL]
1872
difflib Tool for creating delta between sequences.
1873
dis Bytecode disassembler.
1874
distutils Package installation system.
1875
doctest Tool for running and verifying tests inside doc strings.
1876
dospath Common operations on DOS pathnames.
1877
dumbdbm A dumb and slow but simple dbm clone.
1878
[DEL:dump:DEL] [DEL:Print python code that reconstructs a variable.:DEL]
1879
email Comprehensive support for internet email.
1880
exceptions Class based built-in exception hierarchy.
1881
filecmp File comparison.
1882
fileinput Helper class to quickly write a loop over all standard input
1884
[DEL:find:DEL] [DEL:Find files directory hierarchy matching a pattern.:DEL]
1885
fnmatch Filename matching with shell patterns.
1886
formatter A test formatter.
1887
fpformat General floating point formatting functions.
1888
ftplib An FTP client class. Based on RFC 959.
1889
gc Perform garbacge collection, obtain GC debug stats, and tune
1891
getopt Standard command line processing. See also ftp://
1892
www.pauahtun.org/pub/getargspy.zip
1893
getpass Utilities to get a password and/or the current user name.
1894
glob filename globbing.
1895
gopherlib Gopher protocol client interface.
1896
[DEL:grep:DEL] [DEL:'grep' utilities.:DEL]
1897
gzip Read & write gzipped files.
1898
heapq Priority queue implemented using lists organized as heaps.
1899
HMAC Keyed-Hashing for Message Authentication -- RFC 2104.
1900
htmlentitydefs Proposed entity definitions for HTML.
1901
htmllib HTML parsing utilities.
1902
HTMLParser A parser for HTML and XHTML.
1903
httplib HTTP client class.
1904
ihooks Hooks into the "import" mechanism.
1905
imaplib IMAP4 client.Based on RFC 2060.
1906
imghdr Recognizing image files based on their first few bytes.
1907
imputil Privides a way of writing customised import hooks.
1908
inspect Tool for probing live Python objects.
1909
keyword List of Python keywords.
1910
knee A Python re-implementation of hierarchical module import.
1911
linecache Cache lines from files.
1912
linuxaudiodev Lunix /dev/audio support.
1913
locale Support for number formatting using the current locale
1915
logging Python logging facility.
1916
macpath Pathname (or related) operations for the Macintosh.
1917
macurl2path Mac specific module for conversion between pathnames and URLs.
1918
mailbox A class to handle a unix-style or mmdf-style mailbox.
1919
mailcap Mailcap file handling (RFC 1524).
1920
mhlib MH (mailbox) interface.
1921
mimetools Various tools used by MIME-reading or MIME-writing programs.
1922
mimetypes Guess the MIME type of a file.
1923
MimeWriter Generic MIME writer.
1924
mimify Mimification and unmimification of mail messages.
1925
mmap Interface to memory-mapped files - they behave like mutable
1927
multifile Class to make multi-file messages easier to handle.
1928
mutex Mutual exclusion -- for use with module sched.
1930
nntplib An NNTP client class. Based on RFC 977.
1931
ntpath Common operations on DOS pathnames.
1932
nturl2path Mac specific module for conversion between pathnames and URLs.
1933
optparse A comprehensive tool for processing command line options.
1934
os Either mac, dos or posix depending system.
1935
[DEL:packmail: [DEL:Create a self-unpacking shell archive.:DEL]
1937
pdb A Python debugger.
1938
pickle Pickling (save and restore) of Python objects (a faster
1939
Cimplementation exists in built-in module: cPickle).
1940
pipes Conversion pipeline templates.
1941
pkgunil Utilities for working with Python packages.
1942
popen2 variations on pipe open.
1943
poplib A POP3 client class. Based on the J. Myers POP3 draft.
1944
posixfile Extended (posix) file operations.
1945
posixpath Common operations on POSIX pathnames.
1946
pprint Support to pretty-print lists, tuples, & dictionaries
1948
profile Class for profiling python code.
1949
pstats Class for printing reports on profiled python code.
1950
pydoc Utility for generating documentation from source files.
1951
pty Pseudo terminal utilities.
1952
pyexpat Interface to the Expay XML parser.
1953
py_compile Routine to "compile" a .py file to a .pyc file.
1954
pyclbr Parse a Python file and retrieve classes and methods.
1955
Queue A multi-producer, multi-consumer queue.
1956
quopri Conversions to/from quoted-printable transport encoding.
1957
rand Don't use unless you want compatibility with C's rand().
1958
random Random variable generators
1959
re Regular Expressions.
1960
repr Redo repr() but with limits on most sizes.
1961
rexec Restricted execution facilities ("safe" exec, eval, etc).
1962
rfc822 RFC-822 message manipulation class.
1963
rlcompleter Word completion for GNU readline 2.0.
1964
robotparser Parse robots.txt files, useful for web spiders.
1965
sched A generally useful event scheduler class.
1966
sets Module for a set datatype.
1967
sgmllib A parser for SGML.
1968
shelve Manage shelves of pickled objects.
1969
shlex Lexical analyzer class for simple shell-like syntaxes.
1970
shutil Utility functions usable in a shell-like program.
1971
SimpleHTTPServer Simple extension to base http class
1972
site Append module search paths for third-party packages to
1974
smtplib SMTP Client class (RFC 821)
1975
sndhdr Several routines that help recognizing sound.
1976
SocketServer Generic socket server classes.
1977
stat Constants and functions for interpreting stat/lstat struct.
1978
statcache Maintain a cache of file stats.
1979
statvfs Constants for interpreting statvfs struct as returned by
1980
os.statvfs()and os.fstatvfs() (if they exist).
1981
string A collection of string operations.
1982
StringIO File-like objects that read/write a string buffer (a fasterC
1983
implementation exists in built-in module: cStringIO).
1984
sunau Stuff to parse Sun and NeXT audio files.
1985
sunaudio Interpret sun audio headers.
1986
symbol Non-terminal symbols of Python grammar (from "graminit.h").
1987
tabnanny,/font> Check Python source for ambiguous indentation.
1988
tarfile Facility for reading and writing to the *nix tarfile format.
1989
telnetlib TELNET client class. Based on RFC 854.
1990
tempfile Temporary file name allocation.
1991
textwrap Object for wrapping and filling text.
1992
threading Proposed new higher-level threading interfaces
1993
threading_api (doc of the threading module)
1994
toaiff Convert "arbitrary" sound files to AIFF files .
1995
token Tokens (from "token.h").
1996
tokenize Compiles a regular expression that recognizes Python tokens.
1997
traceback Format and print Python stack traces.
1998
tty Terminal utilities.
1999
turtle LogoMation-like turtle graphics
2000
types Define names for all type symbols in the std interpreter.
2001
tzparse Parse a timezone specification.
2002
unicodedata Interface to unicode properties.
2003
urllib Open an arbitrary URL.
2004
urlparse Parse URLs according to latest draft of standard.
2005
user Hook to allow user-specified customization code to run.
2006
UserDict A wrapper to allow subclassing of built-in dict class.
2007
UserList A wrapper to allow subclassing of built-in list class.
2008
UserString A wrapper to allow subclassing of built-in string class.
2009
[DEL:util:DEL] [DEL:some useful functions that don't fit elsewhere !!:DEL]
2010
uu UUencode/UUdecode.
2011
unittest Utilities for implementing unit testing.
2012
wave Stuff to parse WAVE files.
2013
weakref Tools for creating and managing weakly referenced objects.
2014
webbrowser Platform independent URL launcher.
2015
[DEL:whatsound: [DEL:Several routines that help recognizing sound files.:DEL]
2017
whichdb Guess which db package to use to open a db file.
2018
xdrlib Implements (a subset of) Sun XDR (eXternal Data
2020
xmllib A parser for XML, using the derived class as static DTD.
2021
xml.dom Classes for processing XML using the Document Object Model.
2022
xml.sax Classes for processing XML using the SAX API.
2023
xmlrpclib Support for remote procedure calls using XML.
2024
zipfile Read & write PK zipped files.
2025
[DEL:zmod:DEL] [DEL:Demonstration of abstruse mathematical concepts.:DEL]
2031
sys Interpreter state vars and functions
2032
__built-in__ Access to all built-in python identifiers
2033
__main__ Scope of the interpreters main program, script or stdin
2034
array Obj efficiently representing arrays of basic values
2035
math Math functions of C standard
2036
time Time-related functions (also the newer datetime module)
2037
marshal Read and write some python values in binary format
2038
struct Convert between python values and C structs
2042
getopt Parse cmd line args in sys.argv. A la UNIX 'getopt'.
2043
os A more portable interface to OS dependent functionality
2044
re Functions useful for working with regular expressions
2045
string Useful string and characters functions and exceptions
2046
random Mersenne Twister pseudo-random number generator
2047
thread Low-level primitives for working with process threads
2048
threading idem, new recommanded interface.
2052
dbm Interface to Unix ndbm database library
2053
grp Interface to Unix group database
2054
posix OS functionality standardized by C and POSIX standards
2055
posixpath POSIX pathname functions
2056
pwd Access to the Unix password database
2057
select Access to Unix select multiplex file synchronization
2058
socket Access to BSD socket interface
2060
* Tk User-interface Toolkit *
2062
tkinter Main interface to Tk
2066
audioop Useful operations on sound fragments
2067
imageop Useful operations on images
2068
jpeg Access to jpeg image compressor and decompressor
2069
rgbimg Access SGI imglib image files
2071
* Cryptographic Extensions *
2073
md5 Interface to RSA's MD5 message digest algorithm
2074
sha Interface to the SHA message digest algorithm
2075
HMAC Keyed-Hashing for Message Authentication -- RFC 2104.
2077
* SGI IRIX * (4 & 5)
2079
al SGI audio facilities
2081
fl Interface to FORMS library
2083
flp Functions for form designer
2084
fm Access to font manager library
2085
gl Access to graphics library
2087
DEVICE More constants for gl
2088
imgfile Imglib image file interface
2092
sunaudiodev Access to sun audio interface
2095
Workspace exploration and idiom hints
2097
dir(<module>) list functions, variables in <module>
2098
dir() get object keys, defaults to local name space
2099
if __name__ == '__main__': main() invoke main if running as script
2100
map(None, lst1, lst2, ...) merge lists
2101
b = a[:] create copy of seq structure
2102
_ in interactive mode, is last value printed
2110
Python Mode for Emacs
2112
(Not revised, possibly not up to date)
2113
Type C-c ? when in python-mode for extensive help.
2115
Primarily for entering new code:
2116
TAB indent line appropriately
2117
LFD insert newline, then indent
2118
DEL reduce indentation, or delete single character
2119
Primarily for reindenting existing code:
2120
C-c : guess py-indent-offset from file content; change locally
2121
C-u C-c : ditto, but change globally
2122
C-c TAB reindent region to match its context
2123
C-c < shift region left by py-indent-offset
2124
C-c > shift region right by py-indent-offset
2125
MARKING & MANIPULATING REGIONS OF CODE
2126
C-c C-b mark block of lines
2127
M-C-h mark smallest enclosing def
2128
C-u M-C-h mark smallest enclosing class
2129
C-c # comment out region of code
2130
C-u C-c # uncomment region of code
2132
C-c C-p move to statement preceding point
2133
C-c C-n move to statement following point
2134
C-c C-u move up to start of current block
2135
M-C-a move to start of def
2136
C-u M-C-a move to start of class
2137
M-C-e move to end of def
2138
C-u M-C-e move to end of class
2139
EXECUTING PYTHON CODE
2140
C-c C-c sends the entire buffer to the Python interpreter
2141
C-c | sends the current region
2142
C-c ! starts a Python interpreter window; this will be used by
2143
subsequent C-c C-c or C-c | commands
2144
C-c C-w runs PyChecker
2147
py-indent-offset indentation increment
2148
py-block-comment-prefix comment string used by py-comment-region
2149
py-python-command shell command to invoke Python interpreter
2150
py-scroll-process-buffer t means always scroll Python process buffer
2151
py-temp-directory directory used for temp files (if needed)
2152
py-beep-if-tab-change ring the bell if tab-width is changed
2157
(Not revised, possibly not up to date, see 1.5.2 Library Ref section 9.1; in 1.5.2, you may also use debugger integrated in IDLE)
2161
import pdb (it's a module written in Python)
2162
-- defines functions :
2163
run(statement[,globals[, locals]])
2164
-- execute statement string under debugger control, with optional
2165
global & local environment.
2166
runeval(expression[,globals[, locals]])
2167
-- same as run, but evaluate expression and return value.
2168
runcall(function[, argument, ...])
2169
-- run function object with given arg(s)
2170
pm() -- run postmortem on last exception (like debugging a core file)
2172
-- run postmortem on traceback object <t>
2174
-- defines class Pdb :
2175
use Pdb to create reusable debugger objects. Object
2176
preserves state (i.e. break points) between calls.
2178
runs until a breakpoint hit, exception, or end of program
2179
If exception, variable '__exception__' holds (exception,value).
2184
brief reminder of commands
2186
if <arg> numeric, break at line <arg> in current file
2187
if <arg> is function object, break on entry to fcn <arg>
2188
if no arg, list breakpoints
2190
if <arg> numeric, clear breakpoint at <arg> in current file
2191
if no arg, clear all breakpoints after confirmation
2193
print current call stack
2195
move up one stack frame (to top-level caller)
2197
move down one stack frame
2199
advance one line in the program, stepping into calls
2201
advance one line, stepping over calls
2203
continue execution until current function returns
2204
(return value is saved in variable "__return__", which
2205
can be printed or manipulated from debugger)
2207
continue until next breakpoint
2209
Set the next line that will be executed
2211
print args to current function
2213
prints return value from last function that returned
2215
prints value of <arg> in current stack frame
2216
l, list [<first> [, <last>]]
2217
List source code for the current file.
2218
Without arguments, list 11 lines around the current line
2219
or continue the previous listing.
2220
With one argument, list 11 lines starting at that line.
2221
With two arguments, list the given range;
2222
if the second argument is less than the first, it is a count.
2224
prints type of <arg>
2226
executes rest of line as a Python statement in the current stack frame
2228
immediately stop execution and leave debugger
2230
executes last command again
2231
Any input debugger doesn't recognize as a command is assumed to be a
2232
Python statement to execute in the current stack frame, the same way
2233
the exclamation mark ("!") command does.
2238
Python 1.0.3 (Sep 26 1994)
2239
Copyright 1991-1994 Stichting Mathematisch Centrum, Amsterdam
2242
Traceback (innermost last):
2243
File "<stdin>", line 1
2244
File "./rm.py", line 7
2246
File "./rm.py", line 2
2248
ZeroDivisionError: integer division or modulo
2251
> ./rm.py(2)div: return a / r
2265
>>> pdb.runcall(rm.run)
2270
Breakpoints are stored as filename, line number tuples. If a module is reloaded
2271
after editing, any remembered breakpoints are likely to be wrong.
2273
Always single-steps through top-most stack frame. That is, "c" acts like "n".
added
removed
Misc/cheatsheet
