1
"""Extract, format and print information about Python stack traces."""
7
__all__ = ['extract_stack', 'extract_tb', 'format_exception',
8
'format_exception_only', 'format_list', 'format_stack',
9
'format_tb', 'print_exc', 'format_exc', 'print_exception',
10
'print_last', 'print_stack', 'print_tb', 'tb_lineno']
12
def _print(file, str='', terminator='\n'):
13
file.write(str+terminator)
16
def print_list(extracted_list, file=None):
17
"""Print the list of tuples as returned by extract_tb() or
18
extract_stack() as a formatted stack trace to the given file."""
21
for filename, lineno, name, line in extracted_list:
23
' File "%s", line %d, in %s' % (filename,lineno,name))
25
_print(file, ' %s' % line.strip())
27
def format_list(extracted_list):
28
"""Format a list of traceback entry tuples for printing.
30
Given a list of tuples as returned by extract_tb() or
31
extract_stack(), return a list of strings ready for printing.
32
Each string in the resulting list corresponds to the item with the
33
same index in the argument list. Each string ends in a newline;
34
the strings may contain internal newlines as well, for those items
35
whose source text line is not None.
38
for filename, lineno, name, line in extracted_list:
39
item = ' File "%s", line %d, in %s\n' % (filename,lineno,name)
41
item = item + ' %s\n' % line.strip()
46
def print_tb(tb, limit=None, file=None):
47
"""Print up to 'limit' stack trace entries from the traceback 'tb'.
49
If 'limit' is omitted or None, all entries are printed. If 'file'
50
is omitted or None, the output goes to sys.stderr; otherwise
51
'file' should be an open file or file-like object with a write()
57
if hasattr(sys, 'tracebacklimit'):
58
limit = sys.tracebacklimit
60
while tb is not None and (limit is None or n < limit):
64
filename = co.co_filename
67
' File "%s", line %d, in %s' % (filename,lineno,name))
68
linecache.checkcache(filename)
69
line = linecache.getline(filename, lineno, f.f_globals)
70
if line: _print(file, ' ' + line.strip())
74
def format_tb(tb, limit = None):
75
"""A shorthand for 'format_list(extract_stack(f, limit))."""
76
return format_list(extract_tb(tb, limit))
78
def extract_tb(tb, limit = None):
79
"""Return list of up to limit pre-processed entries from traceback.
81
This is useful for alternate formatting of stack traces. If
82
'limit' is omitted or None, all entries are extracted. A
83
pre-processed stack trace entry is a quadruple (filename, line
84
number, function name, text) representing the information that is
85
usually printed for a stack trace. The text is a string with
86
leading and trailing whitespace stripped; if the source is not
90
if hasattr(sys, 'tracebacklimit'):
91
limit = sys.tracebacklimit
94
while tb is not None and (limit is None or n < limit):
98
filename = co.co_filename
100
linecache.checkcache(filename)
101
line = linecache.getline(filename, lineno, f.f_globals)
102
if line: line = line.strip()
104
list.append((filename, lineno, name, line))
110
def print_exception(etype, value, tb, limit=None, file=None):
111
"""Print exception up to 'limit' stack trace entries from 'tb' to 'file'.
113
This differs from print_tb() in the following ways: (1) if
114
traceback is not None, it prints a header "Traceback (most recent
115
call last):"; (2) it prints the exception type and value after the
116
stack trace; (3) if type is SyntaxError and value has the
117
appropriate format, it prints the line where the syntax error
118
occurred with a caret on the next line indicating the approximate
119
position of the error.
124
_print(file, 'Traceback (most recent call last):')
125
print_tb(tb, limit, file)
126
lines = format_exception_only(etype, value)
127
for line in lines[:-1]:
128
_print(file, line, ' ')
129
_print(file, lines[-1], '')
131
def format_exception(etype, value, tb, limit = None):
132
"""Format a stack trace and the exception information.
134
The arguments have the same meaning as the corresponding arguments
135
to print_exception(). The return value is a list of strings, each
136
ending in a newline and some containing internal newlines. When
137
these lines are concatenated and printed, exactly the same text is
138
printed as does print_exception().
141
list = ['Traceback (most recent call last):\n']
142
list = list + format_tb(tb, limit)
145
list = list + format_exception_only(etype, value)
148
def format_exception_only(etype, value):
149
"""Format the exception part of a traceback.
151
The arguments are the exception type and value such as given by
152
sys.last_type and sys.last_value. The return value is a list of
153
strings, each ending in a newline.
155
Normally, the list contains a single string; however, for
156
SyntaxError exceptions, it contains several lines that (when
157
printed) display detailed information about where the syntax
160
The message indicating which exception occurred is always the last
165
# An instance should not have a meaningful value parameter, but
166
# sometimes does, particularly for string exceptions, such as
167
# >>> raise string1, string2 # deprecated
169
# Clear these out first because issubtype(string1, SyntaxError)
170
# would throw another exception and mask the original problem.
171
if (isinstance(etype, BaseException) or
172
isinstance(etype, types.InstanceType) or
173
etype is None or type(etype) is str):
174
return [_format_final_exc_line(etype, value)]
176
stype = etype.__name__
178
if not issubclass(etype, SyntaxError):
179
return [_format_final_exc_line(stype, value)]
181
# It was a syntax error; show exactly where the problem was found.
184
msg, (filename, lineno, offset, badline) = value.args
188
filename = filename or "<string>"
189
lines.append(' File "%s", line %d\n' % (filename, lineno))
190
if badline is not None:
191
lines.append(' %s\n' % badline.strip())
192
if offset is not None:
193
caretspace = badline[:offset].lstrip()
194
# non-space whitespace (likes tabs) must be kept for alignment
195
caretspace = ((c.isspace() and c or ' ') for c in caretspace)
196
# only three spaces to account for offset1 == pos 0
197
lines.append(' %s^\n' % ''.join(caretspace))
200
lines.append(_format_final_exc_line(stype, value))
203
def _format_final_exc_line(etype, value):
204
"""Return a list of a single line -- normal case for format_exception_only"""
205
valuestr = _some_str(value)
206
if value is None or not valuestr:
207
line = "%s\n" % etype
209
line = "%s: %s\n" % (etype, valuestr)
212
def _some_str(value):
216
return '<unprintable %s object>' % type(value).__name__
219
def print_exc(limit=None, file=None):
220
"""Shorthand for 'print_exception(sys.exc_type, sys.exc_value, sys.exc_traceback, limit, file)'.
221
(In fact, it uses sys.exc_info() to retrieve the same information
222
in a thread-safe way.)"""
226
etype, value, tb = sys.exc_info()
227
print_exception(etype, value, tb, limit, file)
229
etype = value = tb = None
232
def format_exc(limit=None):
233
"""Like print_exc() but return a string."""
235
etype, value, tb = sys.exc_info()
236
return ''.join(format_exception(etype, value, tb, limit))
238
etype = value = tb = None
241
def print_last(limit=None, file=None):
242
"""This is a shorthand for 'print_exception(sys.last_type,
243
sys.last_value, sys.last_traceback, limit, file)'."""
246
print_exception(sys.last_type, sys.last_value, sys.last_traceback,
250
def print_stack(f=None, limit=None, file=None):
251
"""Print a stack trace from its invocation point.
253
The optional 'f' argument can be used to specify an alternate
254
stack frame at which to start. The optional 'limit' and 'file'
255
arguments have the same meaning as for print_exception().
259
raise ZeroDivisionError
260
except ZeroDivisionError:
261
f = sys.exc_info()[2].tb_frame.f_back
262
print_list(extract_stack(f, limit), file)
264
def format_stack(f=None, limit=None):
265
"""Shorthand for 'format_list(extract_stack(f, limit))'."""
268
raise ZeroDivisionError
269
except ZeroDivisionError:
270
f = sys.exc_info()[2].tb_frame.f_back
271
return format_list(extract_stack(f, limit))
273
def extract_stack(f=None, limit = None):
274
"""Extract the raw traceback from the current stack frame.
276
The return value has the same format as for extract_tb(). The
277
optional 'f' and 'limit' arguments have the same meaning as for
278
print_stack(). Each item in the list is a quadruple (filename,
279
line number, function name, text), and the entries are in order
280
from oldest to newest stack frame.
284
raise ZeroDivisionError
285
except ZeroDivisionError:
286
f = sys.exc_info()[2].tb_frame.f_back
288
if hasattr(sys, 'tracebacklimit'):
289
limit = sys.tracebacklimit
292
while f is not None and (limit is None or n < limit):
295
filename = co.co_filename
297
linecache.checkcache(filename)
298
line = linecache.getline(filename, lineno, f.f_globals)
299
if line: line = line.strip()
301
list.append((filename, lineno, name, line))
308
"""Calculate correct line number of traceback given in tb.