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""" A Python based configuration file with hierarchical sections. """
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class PyConfigFile(dict):
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""" A Python based configuration file with hierarchical sections. """
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###########################################################################
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###########################################################################
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def __init__(self, file_or_filename=None):
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If 'file_or_filename' is specified it will be loaded immediately. It
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b) a file-like object that must be open for reading
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# A dictionary containing one namespace instance for each root of the
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# config hierarchy (see the '_Namespace' class for more details).
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# e.g. If the following sections have been loaded:-
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# Then the dictionary will contain:-
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# {'acme' : <A _Namespace instance>, 'tds' : <A _Namespace instance>}
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if file_or_filename is not None:
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self.load(file_or_filename)
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###########################################################################
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# 'PyConfigFile' interface.
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###########################################################################
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def load(self, file_or_filename):
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""" Load the configuration from a file.
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'file_or_filename' can be either:-
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b) a file-like object that must be open for reading
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# Get an open file to read from.
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f = self._get_file(file_or_filename)
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stripped = line.strip()
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# Is this line a section header?
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# If so then parse the preceding section (if there is one) and
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# start collecting the body of the new section.
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if stripped.startswith('[') and stripped.endswith(']'):
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if section_name is not None:
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self._parse_section(section_name, section_body)
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section_name = stripped[1:-1]
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# Otherwise, this is *not* a section header so add the line to the
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# body of the current section. If there is no current section then
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# we simply ignore it!
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if section_name is not None:
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# Parse the last section in the file.
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if section_name is not None:
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self._parse_section(section_name, section_body)
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def save(self, file_or_filename):
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""" Save the configuration to a file.
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'file_or_filename' can be either:-
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b) a file-like object that must be open for writing
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f = self._get_file(file_or_filename, 'w')
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for section_name, section_data in self.items():
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self._write_section(f, section_name, section_data)
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###########################################################################
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###########################################################################
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def _get_file(self, file_or_filename, mode='r'):
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""" Return an open file object from a file or a filename.
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The mode is only used if a filename is specified.
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if isinstance(file_or_filename, basestring):
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f = file(file_or_filename, mode)
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def _get_namespace(self, section_name):
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""" Return the namespace that represents the section. """
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components = section_name.split('.')
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namespace = self._namespaces.setdefault(components[0], _Namespace())
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for component in components[1:]:
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namespace = getattr(namespace, component)
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def _parse_section(self, section_name, section_body):
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In this implementation, we don't actually 'parse' anything - we just
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execute the body of the section as Python code ;^)
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# If this is the first time that we have come across the section then
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# start with an empty dictionary for its contents. Otherwise, we will
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# update its existing contents.
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section = self.setdefault(section_name, {})
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# Execute the Python code in the section dictionary.
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# We use 'self._namespaces' as the globals for the code execution so
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# that config values can refer to other config values using familiar
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# Python syntax (see the '_Namespace' class for more details).
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# blitzel = acme.foo.bar + acme.foo.baz
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exec section_body in self._namespaces, section
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# The '__builtins__' dictionary gets added to 'self._namespaces' as
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# by the call to 'exec'. However, we want 'self._namespaces' to only
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# contain '_Namespace' instances, so we do the cleanup here.
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del self._namespaces['__builtins__']
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# Get the section's corresponding node in the 'dotted' namespace and
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# update it with the config values.
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namespace = self._get_namespace(section_name)
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namespace.__dict__.update(section)
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def _write_section(self, f, section_name, section_data):
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""" Write a section to a file. """
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f.write('[%s]\n' % section_name)
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for name, value in section_data.items():
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f.write('%s = %s\n' % (name, repr(value)))
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###########################################################################
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# Debugging interface.
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###########################################################################
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def _pretty_print_namespaces(self):
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""" Pretty print the 'dotted' namespaces. """
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for name, value in self._namespaces.items():
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print 'Namespace:', name
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value.pretty_print(' ')
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###############################################################################
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###############################################################################
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class _Namespace(object):
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""" An object that represents a node in a dotted namespace.
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We build up a dotted namespace so that config values can refer to other
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config values using familiar Python syntax.
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blitzel = acme.foo.bar + acme.foo.baz
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###########################################################################
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# 'object' interface.
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###########################################################################
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def __getattr__(self, name):
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""" Return the attribute with the specified name. """
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# This looks a little weird, but we are simply creating the next level
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# in the namespace hierarchy 'on-demand'.
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namespace = self.__dict__[name] = _Namespace()
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###########################################################################
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# Debugging interface.
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###########################################################################
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def pretty_print(self, indent=''):
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""" Pretty print the namespace. """
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for name, value in self.__dict__.items():
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if isinstance(value, _Namespace):
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print indent, 'Namespace:', name
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value.pretty_print(indent + ' ')
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print indent, name, ':', value
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#### EOF ######################################################################
added
removed
enthought/preferences/tests/py_config_file.py
