:mod:`ConfigParser` --- Configuration file parser

=================================================

.. module:: ConfigParser

   :synopsis: Configuration file parser.

.. moduleauthor:: Ken Manheimer <klm@zope.com>

.. moduleauthor:: Barry Warsaw <bwarsaw@python.org>

.. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>

.. sectionauthor:: Christopher G. Petrilli <petrilli@amber.org>

.. note::

   The :mod:`ConfigParser` module has been renamed to `configparser` in Python

   3.0.  The :term:`2to3` tool will automatically adapt imports when converting

   your sources to 3.0.

.. index::

   pair: .ini; file

   pair: configuration; file

   single: ini file

   single: Windows ini file

This module defines the class :class:`ConfigParser`.   The :class:`ConfigParser`

class implements a basic configuration file parser language which provides a

structure similar to what you would find on Microsoft Windows INI files.  You

can use this to write Python programs which can be customized by end users

easily.

.. warning::

   This library does *not* interpret or write the value-type prefixes used in the

   Windows Registry extended version of INI syntax.

The configuration file consists of sections, led by a ``[section]`` header and

followed by ``name: value`` entries, with continuations in the style of

:rfc:`822` (see section 3.1.1, "LONG HEADER FIELDS"); ``name=value`` is also

accepted.  Note that leading whitespace is removed from values. The optional

values can contain format strings which refer to other values in the same

section, or values in a special ``DEFAULT`` section.  Additional defaults can be

provided on initialization and retrieval.  Lines beginning with ``'#'`` or

``';'`` are ignored and may be used to provide comments.

For example::

   [My Section]

   foodir: %(dir)s/whatever

   dir=frob

   long: this value continues

      in the next line

would resolve the ``%(dir)s`` to the value of ``dir`` (``frob`` in this case).

All reference expansions are done on demand.

Default values can be specified by passing them into the :class:`ConfigParser`

constructor as a dictionary.  Additional defaults  may be passed into the

:meth:`get` method which will override all others.

Sections are normally stored in a builtin dictionary. An alternative dictionary

type can be passed to the :class:`ConfigParser` constructor. For example, if a

dictionary type is passed that sorts its keys, the sections will be sorted on

write-back, as will be the keys within each section.

.. class:: RawConfigParser([defaults[, dict_type]])

   The basic configuration object.  When *defaults* is given, it is initialized

   into the dictionary of intrinsic defaults.  When *dict_type* is given, it will

   be used to create the dictionary objects for the list of sections, for the

   options within a section, and for the default values. This class does not

   support the magical interpolation behavior.

   .. versionadded:: 2.3

   .. versionchanged:: 2.6

      *dict_type* was added.

.. class:: ConfigParser([defaults])

   Derived class of :class:`RawConfigParser` that implements the magical

   interpolation feature and adds optional arguments to the :meth:`get` and

   :meth:`items` methods.  The values in *defaults* must be appropriate for the

   ``%()s`` string interpolation.  Note that *__name__* is an intrinsic default;

   its value is the section name, and will override any value provided in

   *defaults*.

   All option names used in interpolation will be passed through the

   :meth:`optionxform` method just like any other option name reference.  For

   example, using the default implementation of :meth:`optionxform` (which converts

   option names to lower case), the values ``foo %(bar)s`` and ``foo %(BAR)s`` are

   equivalent.

.. class:: SafeConfigParser([defaults])

   Derived class of :class:`ConfigParser` that implements a more-sane variant of

   the magical interpolation feature.  This implementation is more predictable as

   well. New applications should prefer this version if they don't need to be

   compatible with older versions of Python.

   .. XXX Need to explain what's safer/more predictable about it.

   .. versionadded:: 2.3

.. exception:: NoSectionError

   Exception raised when a specified section is not found.

.. exception:: DuplicateSectionError

   Exception raised if :meth:`add_section` is called with the name of a section

   that is already present.

.. exception:: NoOptionError

   Exception raised when a specified option is not found in the specified  section.

.. exception:: InterpolationError

   Base class for exceptions raised when problems occur performing string

   interpolation.

.. exception:: InterpolationDepthError

   Exception raised when string interpolation cannot be completed because the

   number of iterations exceeds :const:`MAX_INTERPOLATION_DEPTH`. Subclass of

   :exc:`InterpolationError`.

.. exception:: InterpolationMissingOptionError

   Exception raised when an option referenced from a value does not exist. Subclass

   of :exc:`InterpolationError`.

   .. versionadded:: 2.3

.. exception:: InterpolationSyntaxError

   Exception raised when the source text into which substitutions are made does not

   conform to the required syntax. Subclass of :exc:`InterpolationError`.

   .. versionadded:: 2.3

.. exception:: MissingSectionHeaderError

   Exception raised when attempting to parse a file which has no section headers.

.. exception:: ParsingError

   Exception raised when errors occur attempting to parse a file.

.. data:: MAX_INTERPOLATION_DEPTH

   The maximum depth for recursive interpolation for :meth:`get` when the *raw*

   parameter is false.  This is relevant only for the :class:`ConfigParser` class.

.. seealso::

   Module :mod:`shlex`

      Support for a creating Unix shell-like mini-languages which can be used as an

      alternate format for application configuration files.

.. _rawconfigparser-objects:

RawConfigParser Objects

-----------------------

:class:`RawConfigParser` instances have the following methods:

.. method:: RawConfigParser.defaults()

   Return a dictionary containing the instance-wide defaults.

.. method:: RawConfigParser.sections()

   Return a list of the sections available; ``DEFAULT`` is not included in the

   list.

.. method:: RawConfigParser.add_section(section)

   Add a section named *section* to the instance.  If a section by the given name

   already exists, :exc:`DuplicateSectionError` is raised. If the name

   ``DEFAULT`` (or any of it's case-insensitive variants) is passed,

   :exc:`ValueError` is raised.

.. method:: RawConfigParser.has_section(section)

   Indicates whether the named section is present in the configuration. The

   ``DEFAULT`` section is not acknowledged.

.. method:: RawConfigParser.options(section)

   Returns a list of options available in the specified *section*.

.. method:: RawConfigParser.has_option(section, option)

   If the given section exists, and contains the given option, return

   :const:`True`; otherwise return :const:`False`.

   .. versionadded:: 1.6

.. method:: RawConfigParser.read(filenames)

   Attempt to read and parse a list of filenames, returning a list of filenames

   which were successfully parsed.  If *filenames* is a string or Unicode string,

   it is treated as a single filename. If a file named in *filenames* cannot be

   opened, that file will be ignored.  This is designed so that you can specify a

   list of potential configuration file locations (for example, the current

   directory, the user's home directory, and some system-wide directory), and all

   existing configuration files in the list will be read.  If none of the named

   files exist, the :class:`ConfigParser` instance will contain an empty dataset.

   An application which requires initial values to be loaded from a file should

   load the required file or files using :meth:`readfp` before calling :meth:`read`

   for any optional files::

      import ConfigParser, os

      config = ConfigParser.ConfigParser()

      config.readfp(open('defaults.cfg'))

      config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')])

   .. versionchanged:: 2.4

      Returns list of successfully parsed filenames.

.. method:: RawConfigParser.readfp(fp[, filename])

   Read and parse configuration data from the file or file-like object in *fp*

   (only the :meth:`readline` method is used).  If *filename* is omitted and *fp*

   has a :attr:`name` attribute, that is used for *filename*; the default is

   ``<???>``.

.. method:: RawConfigParser.get(section, option)

   Get an *option* value for the named *section*.

.. method:: RawConfigParser.getint(section, option)

   A convenience method which coerces the *option* in the specified *section* to an

   integer.

.. method:: RawConfigParser.getfloat(section, option)

   A convenience method which coerces the *option* in the specified *section* to a

   floating point number.

.. method:: RawConfigParser.getboolean(section, option)

   A convenience method which coerces the *option* in the specified *section* to a

   Boolean value.  Note that the accepted values for the option are ``"1"``,

   ``"yes"``, ``"true"``, and ``"on"``, which cause this method to return ``True``,

   and ``"0"``, ``"no"``, ``"false"``, and ``"off"``, which cause it to return

   ``False``.  These string values are checked in a case-insensitive manner.  Any

   other value will cause it to raise :exc:`ValueError`.

.. method:: RawConfigParser.items(section)

   Return a list of ``(name, value)`` pairs for each option in the given *section*.

.. method:: RawConfigParser.set(section, option, value)

   If the given section exists, set the given option to the specified value;

   otherwise raise :exc:`NoSectionError`.  While it is possible to use

   :class:`RawConfigParser` (or :class:`ConfigParser` with *raw* parameters set to

   true) for *internal* storage of non-string values, full functionality (including

   interpolation and output to files) can only be achieved using string values.

   .. versionadded:: 1.6

.. method:: RawConfigParser.write(fileobject)

   Write a representation of the configuration to the specified file object.  This

   representation can be parsed by a future :meth:`read` call.

   .. versionadded:: 1.6

.. method:: RawConfigParser.remove_option(section, option)

   Remove the specified *option* from the specified *section*. If the section does

   not exist, raise :exc:`NoSectionError`.  If the option existed to be removed,

   return :const:`True`; otherwise return :const:`False`.

   .. versionadded:: 1.6

.. method:: RawConfigParser.remove_section(section)

   Remove the specified *section* from the configuration. If the section in fact

   existed, return ``True``. Otherwise return ``False``.

.. method:: RawConfigParser.optionxform(option)

   Transforms the option name *option* as found in an input file or as passed in by

   client code to the form that should be used in the internal structures.  The

   default implementation returns a lower-case version of *option*; subclasses may

   override this or client code can set an attribute of this name on instances to

   affect this behavior.  Setting this to :func:`str`, for example, would make

   option names case sensitive.

.. _configparser-objects:

ConfigParser Objects

--------------------

The :class:`ConfigParser` class extends some methods of the

:class:`RawConfigParser` interface, adding some optional arguments.

.. method:: ConfigParser.get(section, option[, raw[, vars]])

   Get an *option* value for the named *section*.  All the ``'%'`` interpolations

   are expanded in the return values, based on the defaults passed into the

   constructor, as well as the options *vars* provided, unless the *raw* argument

   is true.

.. method:: ConfigParser.items(section[, raw[, vars]])

   Return a list of ``(name, value)`` pairs for each option in the given *section*.

   Optional arguments have the same meaning as for the :meth:`get` method.

   .. versionadded:: 2.3

.. _safeconfigparser-objects:

SafeConfigParser Objects

------------------------

The :class:`SafeConfigParser` class implements the same extended interface as

:class:`ConfigParser`, with the following addition:

.. method:: SafeConfigParser.set(section, option, value)

   If the given section exists, set the given option to the specified value;

   otherwise raise :exc:`NoSectionError`.  *value* must be a string (:class:`str`

   or :class:`unicode`); if not, :exc:`TypeError` is raised.

   .. versionadded:: 2.4

Examples

--------

An example of writing to a configuration file::

   import ConfigParser

   config = ConfigParser.RawConfigParser()

   # When adding sections or items, add them in the reverse order of

   # how you want them to be displayed in the actual file.

   # In addition, please note that using RawConfigParser's and the raw

   # mode of ConfigParser's respective set functions, you can assign

   # non-string values to keys internally, but will receive an error

   # when attempting to write to a file or when you get it in non-raw

   # mode. SafeConfigParser does not allow such assignments to take place.

   config.add_section('Section1')

   config.set('Section1', 'int', '15')

   config.set('Section1', 'bool', 'true')

   config.set('Section1', 'float', '3.1415')

   config.set('Section1', 'baz', 'fun')

   config.set('Section1', 'bar', 'Python')

   config.set('Section1', 'foo', '%(bar)s is %(baz)s!')

   # Writing our configuration file to 'example.cfg'

   with open('example.cfg', 'wb') as configfile:

       config.write(configfile)

An example of reading the configuration file again::

   import ConfigParser

   config = ConfigParser.RawConfigParser()

   config.read('example.cfg')

   # getfloat() raises an exception if the value is not a float

   # getint() and getboolean() also do this for their respective types

   float = config.getfloat('Section1', 'float')

   int = config.getint('Section1', 'int')

   print float + int

   # Notice that the next output does not interpolate '%(bar)s' or '%(baz)s'.

   # This is because we are using a RawConfigParser().

   if config.getboolean('Section1', 'bool'):

       print config.get('Section1', 'foo')

To get interpolation, you will need to use a :class:`ConfigParser` or

:class:`SafeConfigParser`::

   import ConfigParser

   config = ConfigParser.ConfigParser()

   config.read('example.cfg')

   # Set the third, optional argument of get to 1 if you wish to use raw mode.

   print config.get('Section1', 'foo', 0) # -> "Python is fun!"

   print config.get('Section1', 'foo', 1) # -> "%(bar)s is %(baz)s!"

   # The optional fourth argument is a dict with members that will take

   # precedence in interpolation.

   print config.get('Section1', 'foo', 0, {'bar': 'Documentation',

                                           'baz': 'evil'})

Defaults are available in all three types of ConfigParsers. They are used in

interpolation if an option used is not defined elsewhere. ::

   import ConfigParser

   # New instance with 'bar' and 'baz' defaulting to 'Life' and 'hard' each

   config = ConfigParser.SafeConfigParser({'bar': 'Life', 'baz': 'hard'})

   config.read('example.cfg')

   print config.get('Section1', 'foo') # -> "Python is fun!"

   config.remove_option('Section1', 'bar')

   config.remove_option('Section1', 'baz')

   print config.get('Section1', 'foo') # -> "Life is hard!"

The function ``opt_move`` below can be used to move options between sections::

   def opt_move(config, section1, section2, option):

       try:

           config.set(section2, option, config.get(section1, option, 1))

       except ConfigParser.NoSectionError:

           # Create non-existent section

           config.add_section(section2)

           opt_move(config, section1, section2, option)

       else:

           config.remove_option(section1, option)