452 lines
15 KiB
ReStructuredText
452 lines
15 KiB
ReStructuredText
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:mod:`ConfigParser` --- Configuration file parser
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=================================================
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.. module:: ConfigParser
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:synopsis: Configuration file parser.
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.. moduleauthor:: Ken Manheimer <klm@zope.com>
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.. moduleauthor:: Barry Warsaw <bwarsaw@python.org>
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.. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>
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.. sectionauthor:: Christopher G. Petrilli <petrilli@amber.org>
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.. index::
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pair: .ini; file
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pair: configuration; file
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single: ini file
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single: Windows ini file
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This module defines the class :class:`ConfigParser`. The :class:`ConfigParser`
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class implements a basic configuration file parser language which provides a
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structure similar to what you would find on Microsoft Windows INI files. You
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can use this to write Python programs which can be customized by end users
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easily.
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.. warning::
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This library does *not* interpret or write the value-type prefixes used in the
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Windows Registry extended version of INI syntax.
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The configuration file consists of sections, led by a ``[section]`` header and
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followed by ``name: value`` entries, with continuations in the style of
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:rfc:`822`; ``name=value`` is also accepted. Note that leading whitespace is
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removed from values. The optional values can contain format strings which refer
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to other values in the same section, or values in a special ``DEFAULT`` section.
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Additional defaults can be provided on initialization and retrieval. Lines
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beginning with ``'#'`` or ``';'`` are ignored and may be used to provide
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comments.
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For example::
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[My Section]
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foodir: %(dir)s/whatever
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dir=frob
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would resolve the ``%(dir)s`` to the value of ``dir`` (``frob`` in this case).
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All reference expansions are done on demand.
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Default values can be specified by passing them into the :class:`ConfigParser`
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constructor as a dictionary. Additional defaults may be passed into the
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:meth:`get` method which will override all others.
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Sections are normally stored in a builtin dictionary. An alternative dictionary
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type can be passed to the :class:`ConfigParser` constructor. For example, if a
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dictionary type is passed that sorts its keys, the sections will be sorted on
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write-back, as will be the keys within each section.
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.. class:: RawConfigParser([defaults[, dict_type]])
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The basic configuration object. When *defaults* is given, it is initialized
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into the dictionary of intrinsic defaults. When *dict_type* is given, it will
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be used to create the dictionary objects for the list of sections, for the
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options within a section, and for the default values. This class does not
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support the magical interpolation behavior.
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.. versionadded:: 2.3
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.. versionchanged:: 2.6
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*dict_type* was added.
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.. class:: ConfigParser([defaults])
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Derived class of :class:`RawConfigParser` that implements the magical
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interpolation feature and adds optional arguments to the :meth:`get` and
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:meth:`items` methods. The values in *defaults* must be appropriate for the
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``%()s`` string interpolation. Note that *__name__* is an intrinsic default;
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its value is the section name, and will override any value provided in
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*defaults*.
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All option names used in interpolation will be passed through the
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:meth:`optionxform` method just like any other option name reference. For
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example, using the default implementation of :meth:`optionxform` (which converts
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option names to lower case), the values ``foo %(bar)s`` and ``foo %(BAR)s`` are
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equivalent.
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.. class:: SafeConfigParser([defaults])
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Derived class of :class:`ConfigParser` that implements a more-sane variant of
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the magical interpolation feature. This implementation is more predictable as
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well. New applications should prefer this version if they don't need to be
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compatible with older versions of Python.
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.. XXX Need to explain what's safer/more predictable about it.
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.. versionadded:: 2.3
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.. exception:: NoSectionError
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Exception raised when a specified section is not found.
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.. exception:: DuplicateSectionError
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Exception raised if :meth:`add_section` is called with the name of a section
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that is already present.
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.. exception:: NoOptionError
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Exception raised when a specified option is not found in the specified section.
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.. exception:: InterpolationError
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Base class for exceptions raised when problems occur performing string
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interpolation.
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.. exception:: InterpolationDepthError
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Exception raised when string interpolation cannot be completed because the
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number of iterations exceeds :const:`MAX_INTERPOLATION_DEPTH`. Subclass of
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:exc:`InterpolationError`.
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.. exception:: InterpolationMissingOptionError
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Exception raised when an option referenced from a value does not exist. Subclass
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of :exc:`InterpolationError`.
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.. versionadded:: 2.3
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.. exception:: InterpolationSyntaxError
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Exception raised when the source text into which substitutions are made does not
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conform to the required syntax. Subclass of :exc:`InterpolationError`.
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.. versionadded:: 2.3
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.. exception:: MissingSectionHeaderError
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Exception raised when attempting to parse a file which has no section headers.
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.. exception:: ParsingError
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Exception raised when errors occur attempting to parse a file.
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.. data:: MAX_INTERPOLATION_DEPTH
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The maximum depth for recursive interpolation for :meth:`get` when the *raw*
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parameter is false. This is relevant only for the :class:`ConfigParser` class.
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.. seealso::
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Module :mod:`shlex`
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Support for a creating Unix shell-like mini-languages which can be used as an
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alternate format for application configuration files.
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.. _rawconfigparser-objects:
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RawConfigParser Objects
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-----------------------
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:class:`RawConfigParser` instances have the following methods:
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.. method:: RawConfigParser.defaults()
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Return a dictionary containing the instance-wide defaults.
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.. method:: RawConfigParser.sections()
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Return a list of the sections available; ``DEFAULT`` is not included in the
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list.
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.. method:: RawConfigParser.add_section(section)
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Add a section named *section* to the instance. If a section by the given name
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already exists, :exc:`DuplicateSectionError` is raised. If the name
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``DEFAULT`` (or any of it's case-insensitive variants) is passed,
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:exc:`ValueError` is raised.
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.. method:: RawConfigParser.has_section(section)
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Indicates whether the named section is present in the configuration. The
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``DEFAULT`` section is not acknowledged.
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.. method:: RawConfigParser.options(section)
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Returns a list of options available in the specified *section*.
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.. method:: RawConfigParser.has_option(section, option)
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If the given section exists, and contains the given option, return
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:const:`True`; otherwise return :const:`False`.
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.. versionadded:: 1.6
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.. method:: RawConfigParser.read(filenames)
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Attempt to read and parse a list of filenames, returning a list of filenames
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which were successfully parsed. If *filenames* is a string or Unicode string,
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it is treated as a single filename. If a file named in *filenames* cannot be
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opened, that file will be ignored. This is designed so that you can specify a
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list of potential configuration file locations (for example, the current
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directory, the user's home directory, and some system-wide directory), and all
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existing configuration files in the list will be read. If none of the named
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files exist, the :class:`ConfigParser` instance will contain an empty dataset.
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An application which requires initial values to be loaded from a file should
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load the required file or files using :meth:`readfp` before calling :meth:`read`
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for any optional files::
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import ConfigParser, os
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config = ConfigParser.ConfigParser()
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config.readfp(open('defaults.cfg'))
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config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')])
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.. versionchanged:: 2.4
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Returns list of successfully parsed filenames.
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.. method:: RawConfigParser.readfp(fp[, filename])
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Read and parse configuration data from the file or file-like object in *fp*
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(only the :meth:`readline` method is used). If *filename* is omitted and *fp*
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has a :attr:`name` attribute, that is used for *filename*; the default is
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``<???>``.
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.. method:: RawConfigParser.get(section, option)
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Get an *option* value for the named *section*.
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.. method:: RawConfigParser.getint(section, option)
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A convenience method which coerces the *option* in the specified *section* to an
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integer.
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.. method:: RawConfigParser.getfloat(section, option)
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A convenience method which coerces the *option* in the specified *section* to a
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floating point number.
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.. method:: RawConfigParser.getboolean(section, option)
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A convenience method which coerces the *option* in the specified *section* to a
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Boolean value. Note that the accepted values for the option are ``"1"``,
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``"yes"``, ``"true"``, and ``"on"``, which cause this method to return ``True``,
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and ``"0"``, ``"no"``, ``"false"``, and ``"off"``, which cause it to return
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``False``. These string values are checked in a case-insensitive manner. Any
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other value will cause it to raise :exc:`ValueError`.
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.. method:: RawConfigParser.items(section)
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Return a list of ``(name, value)`` pairs for each option in the given *section*.
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.. method:: RawConfigParser.set(section, option, value)
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If the given section exists, set the given option to the specified value;
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otherwise raise :exc:`NoSectionError`. While it is possible to use
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:class:`RawConfigParser` (or :class:`ConfigParser` with *raw* parameters set to
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true) for *internal* storage of non-string values, full functionality (including
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interpolation and output to files) can only be achieved using string values.
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.. versionadded:: 1.6
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.. method:: RawConfigParser.write(fileobject)
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Write a representation of the configuration to the specified file object. This
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representation can be parsed by a future :meth:`read` call.
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.. versionadded:: 1.6
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.. method:: RawConfigParser.remove_option(section, option)
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Remove the specified *option* from the specified *section*. If the section does
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not exist, raise :exc:`NoSectionError`. If the option existed to be removed,
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return :const:`True`; otherwise return :const:`False`.
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.. versionadded:: 1.6
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.. method:: RawConfigParser.remove_section(section)
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Remove the specified *section* from the configuration. If the section in fact
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existed, return ``True``. Otherwise return ``False``.
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.. method:: RawConfigParser.optionxform(option)
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Transforms the option name *option* as found in an input file or as passed in by
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client code to the form that should be used in the internal structures. The
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default implementation returns a lower-case version of *option*; subclasses may
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override this or client code can set an attribute of this name on instances to
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affect this behavior. Setting this to :func:`str`, for example, would make
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option names case sensitive.
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.. _configparser-objects:
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ConfigParser Objects
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--------------------
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The :class:`ConfigParser` class extends some methods of the
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:class:`RawConfigParser` interface, adding some optional arguments.
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.. method:: ConfigParser.get(section, option[, raw[, vars]])
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Get an *option* value for the named *section*. All the ``'%'`` interpolations
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are expanded in the return values, based on the defaults passed into the
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constructor, as well as the options *vars* provided, unless the *raw* argument
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is true.
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.. method:: ConfigParser.items(section[, raw[, vars]])
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Return a list of ``(name, value)`` pairs for each option in the given *section*.
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Optional arguments have the same meaning as for the :meth:`get` method.
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.. versionadded:: 2.3
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.. _safeconfigparser-objects:
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SafeConfigParser Objects
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------------------------
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The :class:`SafeConfigParser` class implements the same extended interface as
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:class:`ConfigParser`, with the following addition:
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.. method:: SafeConfigParser.set(section, option, value)
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If the given section exists, set the given option to the specified value;
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otherwise raise :exc:`NoSectionError`. *value* must be a string (:class:`str`
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or :class:`unicode`); if not, :exc:`TypeError` is raised.
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.. versionadded:: 2.4
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Examples
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--------
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An example of writing to a configuration file::
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import ConfigParser
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config = ConfigParser.RawConfigParser()
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# When adding sections or items, add them in the reverse order of
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# how you want them to be displayed in the actual file.
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# In addition, please note that using RawConfigParser's and the raw
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# mode of ConfigParser's respective set functions, you can assign
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# non-string values to keys internally, but will receive an error
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# when attempting to write to a file or when you get it in non-raw
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# mode. SafeConfigParser does not allow such assignments to take place.
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config.add_section('Section1')
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config.set('Section1', 'int', '15')
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config.set('Section1', 'bool', 'true')
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config.set('Section1', 'float', '3.1415')
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config.set('Section1', 'baz', 'fun')
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config.set('Section1', 'bar', 'Python')
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config.set('Section1', 'foo', '%(bar)s is %(baz)s!')
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# Writing our configuration file to 'example.cfg'
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with open('example.cfg', 'wb') as configfile:
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config.write(configfile)
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An example of reading the configuration file again::
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import ConfigParser
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config = ConfigParser.RawConfigParser()
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config.read('example.cfg')
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# getfloat() raises an exception if the value is not a float
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# getint() and getboolean() also do this for their respective types
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float = config.getfloat('Section1', 'float')
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int = config.getint('Section1', 'int')
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print float + int
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# Notice that the next output does not interpolate '%(bar)s' or '%(baz)s'.
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# This is because we are using a RawConfigParser().
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if config.getboolean('Section1', 'bool'):
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print config.get('Section1', 'foo')
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To get interpolation, you will need to use a :class:`ConfigParser` or
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:class:`SafeConfigParser`::
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import ConfigParser
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config = ConfigParser.ConfigParser()
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config.read('example.cfg')
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# Set the third, optional argument of get to 1 if you wish to use raw mode.
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print config.get('Section1', 'foo', 0) # -> "Python is fun!"
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print config.get('Section1', 'foo', 1) # -> "%(bar)s is %(baz)s!"
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# The optional fourth argument is a dict with members that will take
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# precedence in interpolation.
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print config.get('Section1', 'foo', 0, {'bar': 'Documentation',
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'baz': 'evil'})
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Defaults are available in all three types of ConfigParsers. They are used in
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interpolation if an option used is not defined elsewhere. ::
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import ConfigParser
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# New instance with 'bar' and 'baz' defaulting to 'Life' and 'hard' each
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config = ConfigParser.SafeConfigParser({'bar': 'Life', 'baz': 'hard'})
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config.read('example.cfg')
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print config.get('Section1', 'foo') # -> "Python is fun!"
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config.remove_option('Section1', 'bar')
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config.remove_option('Section1', 'baz')
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print config.get('Section1', 'foo') # -> "Life is hard!"
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The function ``opt_move`` below can be used to move options between sections::
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def opt_move(config, section1, section2, option):
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try:
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config.set(section2, option, config.get(section1, option, 1))
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except ConfigParser.NoSectionError:
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# Create non-existent section
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config.add_section(section2)
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opt_move(config, section1, section2, option)
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else:
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config.remove_option(section1, option)
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