Łukasz Langa avatar Łukasz Langa committed e546f76

Issue #5412: extend configparser to support mapping access

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Doc/library/configparser.rst

 .. moduleauthor:: Ken Manheimer <klm@zope.com>
 .. moduleauthor:: Barry Warsaw <bwarsaw@python.org>
 .. moduleauthor:: Eric S. Raymond <esr@thyrsus.com>
+.. moduleauthor:: Łukasz Langa <lukasz@langa.pl>
 .. sectionauthor:: Christopher G. Petrilli <petrilli@amber.org>
+.. sectionauthor:: Łukasz Langa <lukasz@langa.pl>
 
 .. index::
    pair: .ini; file
    This library does *not* interpret or write the value-type prefixes used in
    the Windows Registry extended version of INI syntax.
 
+.. 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.
+
+Quick Start
+-----------
+
+.. highlightlang:: none
+
+Let's take a very basic configuration file that looks like this::
+
+  [DEFAULT]
+    ServerAliveInterval = 45
+    Compression = yes
+    CompressionLevel = 9
+    ForwardX11 = yes
+
+  [bitbucket.org]
+    User = hg
+
+  [topsecret.server.com]
+    Port = 50022
+    ForwardX11 = no
+
+The supported file structure of INI files is described `in the following section
+<#supported-ini-file-structure>`_, fow now all there's to know is that the file
+consists of sections, each of which contains keys with values.
+:mod:`configparser` classes can read and write such files. Let's start by
+creating the above configuration file programatically.
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> import configparser
+    >>> config = configparser.RawConfigParser()
+    >>> config['DEFAULT'] = {'ServerAliveInterval': '45',
+    ...                      'Compression': 'yes',
+    ...                      'CompressionLevel': '9'}
+    >>> config['bitbucket.org'] = {}
+    >>> config['bitbucket.org']['User'] = 'hg'
+    >>> config['topsecret.server.com'] = {}
+    >>> topsecret = config['topsecret.server.com']
+    >>> topsecret['Port'] = '50022'     # mutates the parser
+    >>> topsecret['ForwardX11'] = 'no'  # same here
+    >>> config['DEFAULT']['ForwardX11'] = 'yes'
+    >>> with open('example.ini', 'w') as configfile:
+    ...   config.write(configfile)
+    ...
+
+As you can see, we can treat a config parser just like a dictionary. There are
+a few differences, `outlined later on <#mapping-protocol-access>`_, but the
+behaviour is very close to what you'd expect from a dictionary.
+
+Now that we've created and saved a configuration file, let's try reading it
+back and exploring the data it holds.
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> import configparser
+    >>> config = configparser.RawConfigParser()
+    >>> config.sections()
+    []
+    >>> config.read('example.ini')
+    ['example.ini']
+    >>> config.sections()
+    ['bitbucket.org', 'topsecret.server.com']
+    >>> 'bitbucket.org' in config
+    True
+    >>> 'bytebong.com' in config
+    False
+    >>> config['bitbucket.org']['User']
+    'hg'
+    >>> config['DEFAULT']['Compression']
+    'yes'
+    >>> topsecret = config['topsecret.server.com']
+    >>> topsecret['ForwardX11']
+    'no'
+    >>> topsecret['Port']
+    '50022'
+    >>> for key in config['bitbucket.org']: print(key)
+    ...
+    user
+    compressionlevel
+    serveraliveinterval
+    compression
+    forwardx11
+    >>> config['bitbucket.org']['ForwardX11']
+    'yes'
+
+As we can see above, the API is pretty straight forward. The only bit of magic
+involves the ``DEFAULT`` section which provides default values for all other
+sections [customizable]_. Another thing to note is that keys in sections are
+case-insensitive so they're stored in lowercase [customizable]_.
+
+Supported Datatypes
+-------------------
+
+Config parsers do not guess datatypes of values in configuration files, always
+storing them internally as strings. This means that if you need other datatypes,
+you should convert on your own:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> int(topsecret['Port'])
+    50022
+    >>> float(topsecret['CompressionLevel'])
+    9.0
+
+Converting to the boolean type is not that simple, though. Wrapping the return
+value around ``bool()`` would do us no good since ``bool('False')`` is still
+``True``. This is why config parsers also provide :meth:`getboolean`. This handy
+method is also case insensitive and correctly recognizes boolean values from
+``'yes'``/``'no'``, ``'on'``/``'off'`` and ``'1'``/``'0'`` [customizable]_.  An
+example of getting the boolean value:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> topsecret.getboolean('ForwardX11')
+    False
+    >>> config['bitbucket.org'].getboolean('ForwardX11')
+    True
+    >>> config.getboolean('bitbucket.org', 'Compression')
+    True
+
+Apart from :meth:`getboolean`, config parsers also provide equivalent
+:meth:`getint` and :meth:`getfloat` methods but these are far less useful
+because explicit casting is enough for these types.
+
+Fallback Values
+---------------
+
+As with a regular dictionary, you can use a section's :meth:`get` method to
+provide fallback values:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> topsecret.get('Port')
+    '50022'
+    >>> topsecret.get('CompressionLevel')
+    '9'
+    >>> topsecret.get('Cipher')
+    >>> topsecret.get('Cipher', '3des-cbc')
+    '3des-cbc'
+
+Please note that default values have precedence over fallback values. For
+instance, in our example the ``CompressionLevel`` key was specified only in the
+``DEFAULT`` section. If we try to get it from the section
+``topsecret.server.com``, we will always get the default, even if we specify
+a fallback:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> topsecret.get('CompressionLevel', '3')
+    '9'
+
+One more thing to be aware of is that the parser-level :meth:`get` method
+provides a custom, more complex interface, maintained for backwards
+compatibility. When using this method, a fallback value can be provided via the
+``fallback`` keyword-only argument:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> config.get('bitbucket.org', 'monster',
+    ...            fallback='No such things as monsters')
+    'No such things as monsters'
+
+The same ``fallback`` argument can be used with the :meth:`getint`,
+:meth:`getfloat` and :meth:`getboolean` methods, for example:
+
+.. highlightlang:: python
+.. doctest::
+
+    >>> 'BatchMode' in topsecret
+    False
+    >>> topsecret.getboolean('BatchMode', fallback=True)
+    True
+    >>> config['DEFAULT']['BatchMode'] = 'no'
+    >>> topsecret.getboolean('BatchMode', fallback=True)
+    False
+
+Supported INI File Structure
+----------------------------
+
 A configuration file consists of sections, each led by a ``[section]`` header,
 followed by key/value entries separated by a specific string (``=`` or ``:`` by
-default). By default, section names are case sensitive but keys are not. Leading
-und trailing whitespace is removed from keys and from values.  Values can be
-omitted, in which case the key/value delimiter may also be left out.  Values
-can also span multiple lines, as long as they are indented deeper than the first
-line of the value.  Depending on the parser's mode, blank lines may be treated
-as parts of multiline values or ignored.
+default [customizable]_). By default, section names are case sensitive but keys
+are not [customizable]_. Leading und trailing whitespace is removed from keys and from values.
+Values can be omitted, in which case the key/value delimiter may also be left
+out.  Values can also span multiple lines, as long as they are indented deeper
+than the first line of the value.  Depending on the parser's mode, blank lines
+may be treated as parts of multiline values or ignored.
 
 Configuration files may include comments, prefixed by specific characters (``#``
-and ``;`` by default).  Comments may appear on their own in an otherwise empty
-line, or may be entered in lines holding values or section names.  In the
-latter case, they need to be preceded by a whitespace character to be recognized
-as a comment.  (For backwards compatibility, by default only ``;`` starts an
-inline comment, while ``#`` does not.)
+and ``;`` by default [customizable]_).  Comments may appear on their own in an
+otherwise empty line, or may be entered in lines holding values or section
+names.  In the latter case, they need to be preceded by a whitespace character
+to be recognized as a comment.  (For backwards compatibility, by default only
+``;`` starts an inline comment, while ``#`` does not [customizable]_.)
 
 On top of the core functionality, :class:`SafeConfigParser` supports
 interpolation.  This means 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.
+other values in the same section, or values in a special ``DEFAULT`` section
+[customizable]_.  Additional defaults can be provided on initialization.
+
+.. highlightlang:: none
 
 For example::
 
             of a value
          # Did I mention we can indent comments, too?
 
-
 In the example above, :class:`SafeConfigParser` would resolve ``%(home_dir)s``
 to the value of ``home_dir`` (``/Users`` in this case).  ``%(my_dir)s`` in
 effect would resolve to ``/Users/lumberjack``.  All interpolations are done on
 ``my_dir``.  Other features presented in the example are handled in the same
 manner by both parsers.
 
-Default values can be specified by passing them as a dictionary when
-constructing the :class:`SafeConfigParser`.
+Mapping Protocol Access
+-----------------------
 
-Sections are normally stored in an :class:`collections.OrderedDict` which
-maintains the order of all keys.  An alternative dictionary type can be passed
-to the :meth:`__init__` method.  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.
+.. versionadded:: 3.2
+.. highlightlang:: python
 
+Mapping protocol access is a generic name for functionality that enables using
+custom objects as if they were dictionaries. In case of :mod:`configparser`,
+the mapping interface implementation is using the
+``parser['section']['option']`` notation.
+
+``parser['section']`` in particular returns a proxy for the section's data in
+the parser. This means that the values are not copied but they are taken from
+the original parser on demand. What's even more important is that when values
+are changed on a section proxy, they are actually mutated in the original
+parser.
+
+:mod:`configparser` objects behave as close to actual dictionaries as possible.
+The mapping interface is complete and adheres to the ``MutableMapping`` ABC.
+However, there are a few differences that should be taken into account:
+
+* by default, all keys in sections are accessible in a case-insensitive manner
+  [customizable]_. E.g. ``for option in parser["section"]`` yields only
+  ``optionxform``'ed option key names. This means lowercased keys by default.
+  At the same time, for a section that holds the key ``"a"``, both expressions
+  return ``True``::
+
+  "a" in parser["section"]
+  "A" in parser["section"]
+
+* all sections include ``DEFAULTSECT`` values as well which means that
+  ``.clear()`` on a section may not leave the section visibly empty. This is
+  because default values cannot be deleted from the section (because technically
+  they are not there). If they are overriden in the section, deleting causes the
+  default value to be visible again. Trying to delete a default value causes
+  a ``KeyError``.
+
+* trying to delete the ``DEFAULTSECT`` throws ``ValueError``
+
+* there are two parser-level methods in the legacy API that hide
+  the dictionary interface and are incompatible:
+
+  * ``parser.get(section, option, **kwargs)`` - the second argument is **not**
+    a fallback value
+
+  * ``parser.items(section)`` - this returns a list of ``(option, value)``
+    pairs for a specified ``section``.
+
+The mapping protocol is implemented on top of the existing legacy API so that
+subclassing the original interface makes the mappings work as expected as well.
+One difference is the explicit lack of support for the `__name__` special key.
+This is because the existing behaviour of `__name__` is very inconsistent and
+supporting it would only lead to problems. Details `here
+<http://mail.python.org/pipermail/python-dev/2010-July/102556.html>`_.
+
+Customizing Parser Behaviour
+----------------------------
+
+There are nearly as many INI format variants as there are applications using it.
+:mod:`configparser` goes a long way to provide support for the largest sensible
+set of INI styles available. The default functionality is mainly dictated by
+historical background and it's very likely that you will want to customize some
+of the features.
+
+The most natural way to change the way a specific config parser works is to use
+the :meth:`__init__` options:
+
+* *defaults*, default value: ``None``
+
+  This option accepts a dictionary of key-value pairs which will be initially
+  put in the ``DEFAULTSECT``. This makes for an elegant way to support concise
+  configuration files that don't specify values which are the same as the
+  documented default.
+
+  Hint: if you want to specify default values for a specific section, use the
+  :meth:`read_dict` before you read the actual file.
+
+* *dict_type*, default value: :class:`collections.OrderedDict`
+
+  This option has a major impact on how the mapping protocol will behave and how
+  the written configuration files will look like. With the default ordered
+  dictionary, every section is stored in the order they were added to the
+  parser. Same goes for options within sections.
+
+  An alternative dictionary type can be used for example to sort sections and
+  options on write-back. You can also use a regular dictionary for performance
+  reasons.
+
+  Please note: there are ways to add a set of key-value pairs in a single
+  operation. When you use a regular dictionary in those operations, the order of
+  the keys may be random. For example:
+
+  .. highlightlang:: python
+  .. doctest::
+
+    >>> parser = configparser.RawConfigParser()
+    >>> parser.read_dict({'section1': {'key1': 'value1',
+    ...                                'key2': 'value2',
+    ...                                'key3': 'value3'},
+    ...                   'section2': {'keyA': 'valueA',
+    ...                                'keyB': 'valueB',
+    ...                                'keyC': 'valueC'},
+    ...                   'section3': {'foo': 'x',
+    ...                                'bar': 'y',
+    ...                                'baz': 'z'}
+    ... })
+    >>> parser.sections()
+    ['section3', 'section2', 'section1']
+    >>> [option for option in parser['section3']]
+    ['baz', 'foo', 'bar']
+
+  In these operations you need to use an ordered dictionary as well:
+
+  .. highlightlang:: python
+  .. doctest::
+
+    >>> from collections import OrderedDict
+    >>> parser = configparser.RawConfigParser()
+    >>> parser.read_dict(
+    ...   OrderedDict((
+    ...     ('s1',
+    ...      OrderedDict((
+    ...        ('1', '2'),
+    ...        ('3', '4'),
+    ...        ('5', '6'),
+    ...      ))
+    ...     ),
+    ...     ('s2',
+    ...      OrderedDict((
+    ...        ('a', 'b'),
+    ...        ('c', 'd'),
+    ...        ('e', 'f'),
+    ...      ))
+    ...     ),
+    ...   ))
+    ... )
+    >>> parser.sections()
+    ['s1', 's2']
+    >>> [option for option in parser['s1']]
+    ['1', '3', '5']
+    >>> [option for option in parser['s2'].values()]
+    ['b', 'd', 'f']
+
+* *allow_no_value*, default value: ``False``
+
+  Some configuration files are known to include settings without values, but
+  which otherwise conform to the syntax supported by :mod:`configparser`.  The
+  *allow_no_value* parameter to the :meth:`__init__` method can be used to
+  indicate that such values should be accepted:
+
+  .. highlightlang:: python
+  .. doctest::
+
+    >>> import configparser
+
+    >>> sample_config = """
+    ... [mysqld]
+    ...   user = mysql
+    ...   pid-file = /var/run/mysqld/mysqld.pid
+    ...   skip-external-locking
+    ...   old_passwords = 1
+    ...   skip-bdb
+    ...   skip-innodb # we don't need ACID today
+    ... """
+    >>> config = configparser.RawConfigParser(allow_no_value=True)
+    >>> config.read_string(sample_config)
+
+    >>> # Settings with values are treated as before:
+    >>> config["mysqld"]["user"]
+    'mysql'
+
+    >>> # Settings without values provide None:
+    >>> config["mysqld"]["skip-bdb"]
+
+    >>> # Settings which aren't specified still raise an error:
+    >>> config["mysqld"]["does-not-exist"]
+    Traceback (most recent call last):
+      ...
+    KeyError: 'does-not-exist'
+
+* *delimiters*, default value: ``('=', ':')``
+
+  Delimiters are substrings that delimit keys from values within a section. The
+  first occurence of a delimiting substring on a line is considered a delimiter.
+  This means values (but not keus) can contain substrings that are in the
+  *delimiters*.
+
+  See also the *space_around_delimiters* argument to
+  :meth:`RawConfigParser.write`.
+
+* *comment_prefixes*, default value: ``_COMPATIBLE`` (``'#'`` valid on empty
+  lines, ``';'`` valid also on non-empty lines)
+
+  Comment prefixes are substrings that indicate the start of a valid comment
+  within a config file. The peculiar default value allows for comments starting
+  with ``'#'`` or ``';'`` but only the latter can be used in a non-empty line.
+  This is obviously dictated by backwards compatibiliy. A more predictable
+  approach would be to specify prefixes as ``('#', ';')`` which will allow for
+  both prefixes to be used in non-empty lines.
+
+  Please note that config parsers don't support escaping of comment prefixes so
+  leaving characters out of *comment_prefixes* is a way of ensuring they can be
+  used as parts of keys or values.
+
+* *strict*, default value: ``False``
+
+  If set to ``True``, the parser will not allow for any section or option
+  duplicates while reading from a single source (using :meth:`read_file`,
+  :meth:`read_string` or :meth:`read_dict`). The default is ``False`` only
+  because of backwards compatibility reasons. It's recommended to use strict
+  parsers in new applications.
+
+* *empty_lines_in_values*, default value: ``True``
+
+  .. highlightlang:: none
+
+  In config parsers, values can be multiline as long as they're indented deeper
+  than the key that holds them. By default parsers also let empty lines to be
+  parts of values. At the same time, keys can be arbitrarily indented themselves
+  to improve readability. In consequence, when configuration files get big and
+  complex, it's easy for the user to lose track of the file structure. Take for
+  instance::
+
+    [Section]
+    key = multiline
+      value with a gotcha
+
+     this = is still a part of the multiline value of 'key'
+
+
+  This can be especially problematic for the user to see if she's using
+  a proportional font to edit the file. That's why when your application does
+  not need values with empty lines, you should consider disallowing them. This
+  will make empty lines split keys every time. In the example above, it would
+  produce two keys, ``key`` and ``this``.
+
+.. highlightlang:: python
+
+More advanced customization may be achieved by overriding default values of the
+following parser members:
+
+* `RawConfigParser.BOOLEAN_STATES`
+
+  By default when using :meth:`getboolean`, config parsers consider the
+  following values ``True``: ``'1'``, ``'yes'``, ``'true'``, ``'on'`` and the
+  following values ``False``: ``'0'``, ``'no'``, ``'false'``, ``'off'``. You can
+  override this by specifying a custom dictionary of strings and their boolean
+  outcomes. For example:
+
+  .. highlightlang:: python
+  .. doctest::
+
+    >>> custom = configparser.RawConfigParser()
+    >>> custom['section1'] = {'funky': 'nope'}
+    >>> custom['section1'].getboolean('funky')
+    Traceback (most recent call last):
+    ...
+    ValueError: Not a boolean: nope
+    >>> custom.BOOLEAN_STATES = {'sure': True, 'nope': False}
+    >>> custom['section1'].getboolean('funky')
+    False
+
+  Other typical boolean pairs include ``accept``/``reject`` or
+  ``enabled``/``disabled``.
+
+* :meth:`RawConfigParser.optionxform`
+
+  This is a method that transforms option names on every read or set operation.
+  By default it converts the name to lowercase. This also means that when
+  a configuration file gets written, all keys will be lowercase. If you find
+  that behaviour unsuitable, you can override this method.  For example:
+
+  .. highlightlang:: python
+  .. doctest::
+
+    >>> config = """
+    ... [Section1]
+    ... Key = Value
+    ...
+    ... [Section2]
+    ... AnotherKey = Value
+    ... """
+    >>> typical = configparser.RawConfigParser()
+    >>> typical.read_string(config)
+    >>> list(typical['Section1'].keys())
+    ['key']
+    >>> list(typical['Section2'].keys())
+    ['anotherkey']
+    >>> custom = configparser.RawConfigParser()
+    >>> custom.optionxform = lambda option: option
+    >>> custom.read_string(config)
+    >>> list(custom['Section1'].keys())
+    ['Key']
+    >>> list(custom['Section2'].keys())
+    ['AnotherKey']
+
+Legacy API Examples
+-------------------
+
+Mainly because of backwards compatibility concerns, :mod:`configparser`
+provides also a legacy API with explicit ``get``/``set`` methods. While there
+are valid use cases for the methods outlined below, mapping protocol access
+is preferred for new projects. The legacy API is at times more advanced,
+low-level and downright counterintuitive.
+
+An example of writing to a configuration file::
+
+   import configparser
+
+   config = configparser.RawConfigParser()
+
+   # 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. Setting values using the
+   # mapping protocol or SafeConfigParser's set() 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', 'w') 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:`SafeConfigParser` or, if
+you absolutely have to, a :class:`ConfigParser`::
+
+   import configparser
+
+   cfg = configparser.SafeConfigParser()
+   cfg.read('example.cfg')
+
+   # Set the optional `raw` argument of get() to True if you wish to disable
+   # interpolation in a single get operation.
+   print(cfg.get('Section1', 'foo', raw=False)) # -> "Python is fun!"
+   print(cfg.get('Section1', 'foo', raw=True))  # -> "%(bar)s is %(baz)s!"
+
+   # The optional `vars` argument is a dict with members that will take
+   # precedence in interpolation.
+   print(cfg.get('Section1', 'foo', vars={'bar': 'Documentation',
+                                             'baz': 'evil'}))
+
+   # The optional `fallback` argument can be used to provide a fallback value
+   print(cfg.get('Section1', 'foo'))
+         # -> "Python is fun!"
+
+   print(cfg.get('Section1', 'foo', fallback='Monty is not.'))
+         # -> "Python is fun!"
+
+   print(cfg.get('Section1', 'monster', fallback='No such things as monsters.'))
+         # -> "No such things as monsters."
+
+   # A bare print(cfg.get('Section1', 'monster')) would raise NoOptionError
+   # but we can also use:
+
+   print(cfg.get('Section1', 'monster', fallback=None))
+         # -> None
+
+
+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!"
+
+.. _rawconfigparser-objects:
+
+RawConfigParser Objects
+-----------------------
 
 .. class:: RawConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)
 
       *empty_lines_in_values* were added.
 
 
-.. class:: SafeConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)
+.. method:: RawConfigParser.defaults()
 
-   Derived class of :class:`ConfigParser` that implements a sane variant of the
-   magical interpolation feature.  This implementation is more predictable as it
-   validates the interpolation syntax used within a configuration file.  This
-   class also enables escaping the interpolation character (e.g. a key can have
-   ``%`` as part of the value by specifying ``%%`` in the file).
+   Return a dictionary containing the instance-wide defaults.
 
-   Applications that don't require interpolation should use
-   :class:`RawConfigParser`, otherwise :class:`SafeConfigParser` is the best
-   option.
 
-   .. versionchanged:: 3.1
-      The default *dict_type* is :class:`collections.OrderedDict`.
+.. 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`.
+
+
+.. method:: RawConfigParser.read(filenames, encoding=None)
+
+   Attempt to read and parse a list of filenames, returning a list of filenames
+   which were successfully parsed.  If *filenames* is a 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:`read_file` before calling
+   :meth:`read` for any optional files::
+
+      import configparser, os
+
+      config = configparser.ConfigParser()
+      config.read_file(open('defaults.cfg'))
+      config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')], encoding='cp1250')
+
+   .. versionadded:: 3.2
+      The *encoding* parameter.  Previously, all files were read using the
+      default encoding for :func:`open`.
+
+
+.. method:: RawConfigParser.read_file(f, source=None)
+
+   Read and parse configuration data from the file or file-like object in *f*
+   (only the :meth:`readline` method is used).  The file-like object must
+   operate in text mode, i.e. return strings from :meth:`readline`.
+
+   Optional argument *source* specifies the name of the file being read. It not
+   given and *f* has a :attr:`name` attribute, that is used for *source*; the
+   default is ``<???>``.
+
+   .. versionadded:: 3.2
+      Renamed from :meth:`readfp` (with the ``filename`` attribute renamed to
+      ``source`` for consistency with other ``read_*`` methods).
+
+
+.. method:: RawConfigParser.read_string(string, source='<string>')
+
+   Parse configuration data from a given string.
+
+   Optional argument *source* specifies a context-specific name of the string
+   passed. If not given, ``<string>`` is used.
+
+   .. versionadded:: 3.2
+
+
+.. method:: RawConfigParser.read_dict(dictionary, source='<dict>')
+
+   Load configuration from a dictionary. Keys are section names, values are
+   dictionaries with keys and values that should be present in the section. If
+   the used dictionary type preserves order, sections and their keys will be
+   added in order. Values are automatically converted to strings.
+
+   Optional argument *source* specifies a context-specific name of the
+   dictionary passed.  If not given, ``<dict>`` is used.
+
+   .. versionadded:: 3.2
+
+.. method:: RawConfigParser.get(section, option, [vars, fallback])
+
+   Get an *option* value for the named *section*. If *vars* is provided, it
+   must be a dictionary.  The *option* is looked up in *vars* (if provided),
+   *section*, and in *DEFAULTSECT* in that order. If the key is not found and
+   *fallback* is provided, it is used as a fallback value. ``None`` can be
+   provided as a *fallback* value.
 
    .. versionchanged:: 3.2
-      *allow_no_value*, *delimiters*, *comment_prefixes*, *strict* and
-      *empty_lines_in_values* were added.
+      Arguments *vars* and *fallback* are keyword only to protect users from
+      trying to use the third argument as the *fallback* fallback (especially
+      when using the mapping protocol).
 
 
+.. method:: RawConfigParser.getint(section, option, [vars, fallback])
+
+   A convenience method which coerces the *option* in the specified *section* to
+   an integer. See :meth:`get` for explanation of *vars* and *fallback*.
+
+
+.. method:: RawConfigParser.getfloat(section, option, [vars, fallback])
+
+   A convenience method which coerces the *option* in the specified *section* to
+   a floating point number.  See :meth:`get` for explanation of *vars* and
+   *fallback*.
+
+
+.. method:: RawConfigParser.getboolean(section, option, [vars, fallback])
+
+   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`. See :meth:`get` for explanation of *vars* and *fallback*.
+
+
+.. 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.
+
+.. warning::
+
+   This method lets users assign non-string values to keys internally. This
+   behaviour is unsupported and will cause errors when attempting to write to
+   a file or get it in non-raw mode. **Use the mapping protocol API** which does
+   not allow such assignments to take place.
+
+
+.. method:: RawConfigParser.write(fileobject, space_around_delimiters=True)
+
+   Write a representation of the configuration to the specified
+   :term:`file object`, which must be opened in text mode (accepting strings).
+   This representation can be parsed by a future :meth:`read` call. If
+   ``space_around_delimiters`` is ``True`` (the default), delimiters between
+   keys and values are surrounded by spaces.
+
+
+.. 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`.
+
+
+.. 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.
+
+   You don't necessarily need to subclass a ConfigParser to use this method, you
+   can also re-set it on an instance, to a function that takes a string
+   argument.  Setting it to ``str``, for example, would make option names case
+   sensitive::
+
+      cfgparser = ConfigParser()
+      ...
+      cfgparser.optionxform = str
+
+   Note that when reading configuration files, whitespace around the
+   option names are stripped before :meth:`optionxform` is called.
+
+
+.. method:: RawConfigParser.readfp(fp, filename=None)
+
+   .. deprecated:: 3.2
+      Please use :meth:`read_file` instead.
+
+
+.. _configparser-objects:
+
+ConfigParser Objects
+--------------------
+
+.. warning::
+   Whenever you can, consider using :class:`SafeConfigParser` which
+   adds validation and escaping for the interpolation.
+
+The :class:`ConfigParser` class extends some methods of the
+:class:`RawConfigParser` interface, adding some optional arguments.
+
 .. class:: ConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)
 
    Derived class of :class:`RawConfigParser` that implements the magical
       *strict* and *empty_lines_in_values* were added.
 
 
+.. method:: ConfigParser.get(section, option, raw=False, [vars, fallback])
+
+   Get an *option* value for the named *section*.  If *vars* is provided, it
+   must be a dictionary.  The *option* is looked up in *vars* (if provided),
+   *section*, and in *DEFAULTSECT* in that order. If the key is not found and
+   *fallback* is provided, it is used as a fallback value. ``None`` can be
+   provided as a *fallback* value.
+
+   All the ``'%'`` interpolations are expanded in the return values, unless the
+   *raw* argument is true.  Values for interpolation keys are looked up in the
+   same manner as the option.
+
+   .. versionchanged:: 3.2
+      Arguments *raw*, *vars* and *fallback* are keyword only to protect users
+      from trying to use the third argument as the *fallback* fallback
+      (especially when using the mapping protocol).
+
+
+.. method:: ConfigParser.getint(section, option, raw=False, [vars, fallback])
+
+   A convenience method which coerces the *option* in the specified *section* to
+   an integer. See :meth:`get` for explanation of *raw*, *vars* and *fallback*.
+
+
+.. method:: ConfigParser.getfloat(section, option, raw=False, [vars, fallback])
+
+   A convenience method which coerces the *option* in the specified *section* to
+   a floating point number. See :meth:`get` for explanation of *raw*, *vars*
+   and *fallback*.
+
+
+.. method:: ConfigParser.getboolean(section, option, raw=False, [vars, fallback])
+
+   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`. See :meth:`get` for explanation of *raw*, *vars* and
+   *fallback*.
+
+
+.. method:: ConfigParser.items(section, raw=False, vars=None)
+
+   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.
+
+
+.. 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.
+
+.. _safeconfigparser-objects:
+
+SafeConfigParser Objects
+------------------------
+
+.. class:: SafeConfigParser(defaults=None, dict_type=collections.OrderedDict, allow_no_value=False, delimiters=('=', ':'), comment_prefixes=_COMPATIBLE, strict=False, empty_lines_in_values=True)
+
+   Derived class of :class:`ConfigParser` that implements a sane variant of the
+   magical interpolation feature.  This implementation is more predictable as it
+   validates the interpolation syntax used within a configuration file.  This
+   class also enables escaping the interpolation character (e.g. a key can have
+   ``%`` as part of the value by specifying ``%%`` in the file).
+
+   Applications that don't require interpolation should use
+   :class:`RawConfigParser`, otherwise :class:`SafeConfigParser` is the best
+   option.
+
+   .. versionchanged:: 3.1
+      The default *dict_type* is :class:`collections.OrderedDict`.
+
+   .. versionchanged:: 3.2
+      *allow_no_value*, *delimiters*, *comment_prefixes*, *strict* and
+      *empty_lines_in_values* were added.
+
+
+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; if it is
+   not, :exc:`TypeError` is raised.
+
+
+Exceptions
+----------
+
 .. exception:: Error
 
    Base class for all other configparser exceptions.
       The ``filename`` attribute and :meth:`__init__` argument were renamed to
       ``source`` for consistency.
 
-.. 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`.
-
-
-.. method:: RawConfigParser.read(filenames, encoding=None)
-
-   Attempt to read and parse a list of filenames, returning a list of filenames
-   which were successfully parsed.  If *filenames* is a 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:`read_file` before calling
-   :meth:`read` for any optional files::
-
-      import configparser, os
-
-      config = configparser.ConfigParser()
-      config.read_file(open('defaults.cfg'))
-      config.read(['site.cfg', os.path.expanduser('~/.myapp.cfg')], encoding='cp1250')
-
-   .. versionadded:: 3.2
-      The *encoding* parameter.  Previously, all files were read using the
-      default encoding for :func:`open`.
-
-
-.. method:: RawConfigParser.read_file(f, source=None)
-
-   Read and parse configuration data from the file or file-like object in *f*
-   (only the :meth:`readline` method is used).  The file-like object must
-   operate in text mode, i.e. return strings from :meth:`readline`.
-
-   Optional argument *source* specifies the name of the file being read. It not
-   given and *f* has a :attr:`name` attribute, that is used for *source*; the
-   default is ``<???>``.
-
-   .. versionadded:: 3.2
-      Renamed from :meth:`readfp` (with the ``filename`` attribute renamed to
-      ``source`` for consistency with other ``read_*`` methods).
-
-
-.. method:: RawConfigParser.read_string(string, source='<string>')
-
-   Parse configuration data from a given string.
-
-   Optional argument *source* specifies a context-specific name of the string
-   passed. If not given, ``<string>`` is used.
-
-   .. versionadded:: 3.2
-
-
-.. method:: RawConfigParser.read_dict(dictionary, source='<dict>')
-
-   Load configuration from a dictionary. Keys are section names, values are
-   dictionaries with keys and values that should be present in the section. If
-   the used dictionary type preserves order, sections and their keys will be
-   added in order. Values are automatically converted to strings.
-
-   Optional argument *source* specifies a context-specific name of the
-   dictionary passed.  If not given, ``<dict>`` is used.
-
-   .. versionadded:: 3.2
-
-.. method:: RawConfigParser.get(section, option, [vars, default])
-
-   Get an *option* value for the named *section*. If *vars* is provided, it
-   must be a dictionary.  The *option* is looked up in *vars* (if provided),
-   *section*, and in *DEFAULTSECT* in that order. If the key is not found and
-   *default* is provided, it is used as a fallback value. ``None`` can be
-   provided as a *default* value.
-
-
-.. method:: RawConfigParser.getint(section, option, [vars, default])
-
-   A convenience method which coerces the *option* in the specified *section* to
-   an integer. See :meth:`get` for explanation of *vars* and *default*.
-
-
-.. method:: RawConfigParser.getfloat(section, option, [vars, default])
-
-   A convenience method which coerces the *option* in the specified *section* to
-   a floating point number.  See :meth:`get` for explanation of *vars* and
-   *default*.
-
-
-.. method:: RawConfigParser.getboolean(section, option, [vars, default])
-
-   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`. See :meth:`get` for explanation of *vars* and *default*.
-
-
-.. 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.
-
-
-.. method:: RawConfigParser.write(fileobject, space_around_delimiters=True)
-
-   Write a representation of the configuration to the specified :term:`file object`,
-   which must be opened in text mode (accepting strings).  This representation
-   can be parsed by a future :meth:`read` call. If ``space_around_delimiters``
-   is ``True`` (the default), delimiters between keys and values are surrounded
-   by spaces.
-
-
-.. 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`.
-
-
-.. 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.
-
-   You don't necessarily need to subclass a ConfigParser to use this method, you
-   can also re-set it on an instance, to a function that takes a string
-   argument.  Setting it to ``str``, for example, would make option names case
-   sensitive::
-
-      cfgparser = ConfigParser()
-      ...
-      cfgparser.optionxform = str
-
-   Note that when reading configuration files, whitespace around the
-   option names are stripped before :meth:`optionxform` is called.
-
-
-.. method:: RawConfigParser.readfp(fp, filename=None)
-
-   .. deprecated:: 3.2
-      Please use :meth:`read_file` instead.
-
-
-.. _configparser-objects:
-
-ConfigParser Objects
---------------------
-
-The :class:`ConfigParser` class extends some methods of the
-:class:`RawConfigParser` interface, adding some optional arguments. Whenever you
-can, consider using :class:`SafeConfigParser` which adds validation and escaping
-for the interpolation.
-
-
-.. method:: ConfigParser.get(section, option, raw=False, [vars, default])
-
-   Get an *option* value for the named *section*.  If *vars* is provided, it
-   must be a dictionary.  The *option* is looked up in *vars* (if provided),
-   *section*, and in *DEFAULTSECT* in that order. If the key is not found and
-   *default* is provided, it is used as a fallback value. ``None`` can be
-   provided as a *default* value.
-
-   All the ``'%'`` interpolations are expanded in the return values, unless the
-   *raw* argument is true.  Values for interpolation keys are looked up in the
-   same manner as the option.
-
-
-.. method:: ConfigParser.getint(section, option, raw=False, [vars, default])
-
-   A convenience method which coerces the *option* in the specified *section* to
-   an integer. See :meth:`get` for explanation of *raw*, *vars* and *default*.
-
-
-.. method:: ConfigParser.getfloat(section, option, raw=False, [vars, default])
-
-   A convenience method which coerces the *option* in the specified *section* to
-   a floating point number. See :meth:`get` for explanation of *raw*, *vars*
-   and *default*.
-
-
-.. method:: ConfigParser.getboolean(section, option, raw=False, [vars, default])
-
-   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`. See :meth:`get` for explanation of *raw*, *vars* and
-   *default*.
-
-
-.. method:: ConfigParser.items(section, raw=False, vars=None)
-
-   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.
-
-
-.. _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; if it is
-   not, :exc:`TypeError` is raised.
-
-
-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', 'w') 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)
-
-Some configuration files are known to include settings without values, but which
-otherwise conform to the syntax supported by :mod:`configparser`.  The
-*allow_no_value* parameter to the :meth:`__init__` method can be used to
-indicate that such values should be accepted:
-
-.. doctest::
-
-   >>> import configparser
-   >>> import io
-
-   >>> sample_config = """
-   ... [mysqld]
-   ...   user = mysql
-   ...   pid-file = /var/run/mysqld/mysqld.pid
-   ...   skip-external-locking
-   ...   old_passwords = 1
-   ...   skip-bdb
-   ...   skip-innodb # we don't need ACID today
-   ... """
-   >>> config = configparser.RawConfigParser(allow_no_value=True)
-   >>> config.read_file(io.BytesIO(sample_config))
-
-   >>> # Settings with values are treated as before:
-   >>> config.get("mysqld", "user")
-   'mysql'
-
-   >>> # Settings without values provide None:
-   >>> config.get("mysqld", "skip-bdb")
-
-   >>> # Settings which aren't specified still raise an error:
-   >>> config.get("mysqld", "does-not-exist")
-   Traceback (most recent call last):
-     ...
-   configparser.NoOptionError: No option 'does-not-exist' in section: 'mysqld'
+.. [customizable] Config parsers allow for very heavy customization. If you're
+                  interested in changing the behaviour outlined by the footnote
+                  reference, consult the `Customizing Parser Behaviour`_ section.

Lib/configparser.py

         and their keys will be added in order. Values are automatically
         converted to strings.
 
-    get(section, option, raw=False, vars=None, default=_UNSET)
+    get(section, option, raw=False, vars=None, fallback=_UNSET)
         Return a string value for the named option.  All % interpolations are
         expanded in the return values, based on the defaults passed into the
         constructor and the DEFAULT section.  Additional substitutions may be
         contents override any pre-existing defaults. If `option' is a key in
         `vars', the value from `vars' is used.
 
-    getint(section, options, raw=False, vars=None, default=_UNSET)
+    getint(section, options, raw=False, vars=None, fallback=_UNSET)
         Like get(), but convert value to an integer.
 
-    getfloat(section, options, raw=False, vars=None, default=_UNSET)
+    getfloat(section, options, raw=False, vars=None, fallback=_UNSET)
         Like get(), but convert value to a float.
 
-    getboolean(section, options, raw=False, vars=None, default=_UNSET)
+    getboolean(section, options, raw=False, vars=None, fallback=_UNSET)
         Like get(), but convert value to a boolean (currently case
         insensitively defined as 0, false, no, off for False, and 1, true,
         yes, on for True).  Returns False or True.
         between keys and values are surrounded by spaces.
 """
 
-try:
-    from collections import OrderedDict as _default_dict
-except ImportError:
-    # fallback for setup.py which hasn't yet built _collections
-    _default_dict = dict
-
+from collections import MutableMapping, OrderedDict as _default_dict
+import functools
 import io
+import itertools
 import re
 import sys
 import warnings
 _UNSET = object()
 
 
-class RawConfigParser:
+class RawConfigParser(MutableMapping):
     """ConfigParser that does not do interpolation."""
 
     # Regular expressions for parsing section headers and options
         self._dict = dict_type
         self._sections = self._dict()
         self._defaults = self._dict()
+        self._views = self._dict()
+        self._views[DEFAULTSECT] = SectionProxy(self, DEFAULTSECT)
         if defaults:
             for key, value in defaults.items():
                 self._defaults[self.optionxform(key)] = value
             self._startonly_comment_prefixes = ()
             self._comment_prefixes = tuple(comment_prefixes or ())
         self._strict = strict
+        self._allow_no_value = allow_no_value
         self._empty_lines_in_values = empty_lines_in_values
 
     def defaults(self):
         already exists. Raise ValueError if name is DEFAULT or any of it's
         case-insensitive variants.
         """
-        if section.lower() == "default":
+        if section.upper() == DEFAULTSECT:
             raise ValueError('Invalid section name: %s' % section)
 
         if section in self._sections:
             raise DuplicateSectionError(section)
         self._sections[section] = self._dict()
+        self._views[section] = SectionProxy(self, section)
 
     def has_section(self, section):
         """Indicate whether the named section is present in the configuration.
         for section, keys in dictionary.items():
             try:
                 self.add_section(section)
-            except DuplicateSectionError:
+            except (DuplicateSectionError, ValueError):
                 if self._strict and section in elements_added:
                     raise
                 elements_added.add(section)
         )
         self.read_file(fp, source=filename)
 
-    def get(self, section, option, vars=None, default=_UNSET):
+    def get(self, section, option, *, vars=None, fallback=_UNSET):
         """Get an option value for a given section.
 
         If `vars' is provided, it must be a dictionary. The option is looked up
         in `vars' (if provided), `section', and in `DEFAULTSECT' in that order.
-        If the key is not found and `default' is provided, it is used as
-        a fallback value. `None' can be provided as a `default' value.
+        If the key is not found and `fallback' is provided, it is used as
+        a fallback value. `None' can be provided as a `fallback' value.
+
+        Arguments `vars' and `fallback' are keyword only.
         """
         try:
             d = self._unify_values(section, vars)
         except NoSectionError:
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
         option = self.optionxform(option)
         try:
             return d[option]
         except KeyError:
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise NoOptionError(option, section)
             else:
-                return default
+                return fallback
 
     def items(self, section):
         try:
             del d["__name__"]
         return d.items()
 
-    def _get(self, section, conv, option, *args, **kwargs):
-        return conv(self.get(section, option, *args, **kwargs))
+    def _get(self, section, conv, option, **kwargs):
+        return conv(self.get(section, option, **kwargs))
 
-    def getint(self, section, option, vars=None, default=_UNSET):
+    def getint(self, section, option, *, vars=None, fallback=_UNSET):
         try:
-            return self._get(section, int, option, vars)
+            return self._get(section, int, option, vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
-    def getfloat(self, section, option, vars=None, default=_UNSET):
+    def getfloat(self, section, option, *, vars=None, fallback=_UNSET):
         try:
-            return self._get(section, float, option, vars)
+            return self._get(section, float, option, vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
-    def getboolean(self, section, option, vars=None, default=_UNSET):
+    def getboolean(self, section, option, *, vars=None, fallback=_UNSET):
         try:
-            return self._get(section, self._convert_to_boolean, option, vars)
+            return self._get(section, self._convert_to_boolean, option,
+                             vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
     def optionxform(self, optionstr):
         return optionstr.lower()
         for key, value in section_items:
             if key == "__name__":
                 continue
-            if (value is not None) or (self._optcre == self.OPTCRE):
+            if value is not None or not self._allow_no_value:
                 value = delimiter + str(value).replace('\n', '\n\t')
             else:
                 value = ""
         existed = section in self._sections
         if existed:
             del self._sections[section]
+            del self._views[section]
         return existed
 
+    def __getitem__(self, key):
+        if key != DEFAULTSECT and not self.has_section(key):
+            raise KeyError(key)
+        return self._views[key]
+
+    def __setitem__(self, key, value):
+        # To conform with the mapping protocol, overwrites existing values in
+        # the section.
+
+        # XXX this is not atomic if read_dict fails at any point. Then again,
+        # no update method in configparser is atomic in this implementation.
+        self.remove_section(key)
+        self.read_dict({key: value})
+
+    def __delitem__(self, key):
+        if key == DEFAULTSECT:
+            raise ValueError("Cannot remove the default section.")
+        if not self.has_section(key):
+            raise KeyError(key)
+        self.remove_section(key)
+
+    def __contains__(self, key):
+        return key == DEFAULTSECT or self.has_section(key)
+
+    def __len__(self):
+        return len(self._sections) + 1 # the default section
+
+    def __iter__(self):
+        # XXX does it break when underlying container state changed?
+        return itertools.chain((DEFAULTSECT,), self._sections.keys())
+
     def _read(self, fp, fpname):
         """Parse a sectioned configuration file.
 
                         cursect = self._dict()
                         cursect['__name__'] = sectname
                         self._sections[sectname] = cursect
+                        self._views[sectname] = SectionProxy(self, sectname)
                         elements_added.add(sectname)
                     # So sections can't start with a continuation line
                     optname = None
         self._join_multiline_values()
 
     def _join_multiline_values(self):
-        all_sections = [self._defaults]
-        all_sections.extend(self._sections.values())
+        all_sections = itertools.chain((self._defaults,),
+                                       self._sections.values())
         for options in all_sections:
             for name, val in options.items():
                 if isinstance(val, list):
             raise ValueError('Not a boolean: %s' % value)
         return self.BOOLEAN_STATES[value.lower()]
 
+    def _validate_value_type(self, value):
+        """Raises a TypeError for non-string values.
+
+        The only legal non-string value if we allow valueless
+        options is None, so we need to check if the value is a
+        string if:
+        - we do not allow valueless options, or
+        - we allow valueless options but the value is not None
+
+        For compatibility reasons this method is not used in classic set()
+        for RawConfigParsers and ConfigParsers. It is invoked in every
+        case for mapping protocol access and in SafeConfigParser.set().
+        """
+        if not self._allow_no_value or value:
+            if not isinstance(value, str):
+                raise TypeError("option values must be strings")
+
+
 
 class ConfigParser(RawConfigParser):
     """ConfigParser implementing interpolation."""
 
-    def get(self, section, option, raw=False, vars=None, default=_UNSET):
+    def get(self, section, option, *, raw=False, vars=None, fallback=_UNSET):
         """Get an option value for a given section.
 
         If `vars' is provided, it must be a dictionary. The option is looked up
         in `vars' (if provided), `section', and in `DEFAULTSECT' in that order.
-        If the key is not found and `default' is provided, it is used as
-        a fallback value. `None' can be provided as a `default' value.
+        If the key is not found and `fallback' is provided, it is used as
+        a fallback value. `None' can be provided as a `fallback' value.
 
         All % interpolations are expanded in the return values, unless the
         optional argument `raw' is true.  Values for interpolation keys are
         looked up in the same manner as the option.
 
+        Arguments `raw', `vars', and `fallback' are keyword only.
+
         The section DEFAULT is special.
         """
         try:
             d = self._unify_values(section, vars)
         except NoSectionError:
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
         option = self.optionxform(option)
         try:
             value = d[option]
         except KeyError:
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise NoOptionError(option, section)
             else:
-                return default
+                return fallback
 
         if raw or value is None:
             return value
         else:
             return self._interpolate(section, option, value, d)
 
-    def getint(self, section, option, raw=False, vars=None, default=_UNSET):
+    def getint(self, section, option, *, raw=False, vars=None,
+               fallback=_UNSET):
         try:
-            return self._get(section, int, option, raw, vars)
+            return self._get(section, int, option, raw=raw, vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
-    def getfloat(self, section, option, raw=False, vars=None, default=_UNSET):
+    def getfloat(self, section, option, *, raw=False, vars=None,
+                 fallback=_UNSET):
         try:
-            return self._get(section, float, option, raw, vars)
+            return self._get(section, float, option, raw=raw, vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
-    def getboolean(self, section, option, raw=False, vars=None,
-                   default=_UNSET):
+    def getboolean(self, section, option, *, raw=False, vars=None,
+                   fallback=_UNSET):
         try:
-            return self._get(section, self._convert_to_boolean, option, raw,
-                             vars)
+            return self._get(section, self._convert_to_boolean, option,
+                             raw=raw, vars=vars)
         except (NoSectionError, NoOptionError):
-            if default is _UNSET:
+            if fallback is _UNSET:
                 raise
             else:
-                return default
+                return fallback
 
     def items(self, section, raw=False, vars=None):
         """Return a list of (name, value) tuples for each option in a section.
 
     def set(self, section, option, value=None):
         """Set an option.  Extend ConfigParser.set: check for string values."""
-        # The only legal non-string value if we allow valueless
-        # options is None, so we need to check if the value is a
-        # string if:
-        # - we do not allow valueless options, or
-        # - we allow valueless options but the value is not None
-        if self._optcre is self.OPTCRE or value:
-            if not isinstance(value, str):
-                raise TypeError("option values must be strings")
+        self._validate_value_type(value)
         # check for bad percent signs
         if value:
             tmp_value = value.replace('%%', '') # escaped percent signs
                 raise ValueError("invalid interpolation syntax in %r at "
                                 "position %d" % (value, tmp_value.find('%')))
         ConfigParser.set(self, section, option, value)
+
+
+class SectionProxy(MutableMapping):
+    """A proxy for a single section from a parser."""
+
+    _noname = ("__name__ special key access and modification "
+               "not supported through the mapping interface.")
+
+    def __init__(self, parser, section_name):
+        """Creates a view on a section named `section_name` in `parser`."""
+        self._parser = parser
+        self._section = section_name
+        self.getint = functools.partial(self._parser.getint,
+                                        self._section)
+        self.getfloat = functools.partial(self._parser.getfloat,
+                                          self._section)
+        self.getboolean = functools.partial(self._parser.getboolean,
+                                            self._section)
+
+    def __repr__(self):
+        return '<Section: {}>'.format(self._section)
+
+    def __getitem__(self, key):
+        if key == '__name__':
+            raise ValueError(self._noname)
+        if not self._parser.has_option(self._section, key):
+            raise KeyError(key)
+        return self._parser.get(self._section, key)
+
+    def __setitem__(self, key, value):
+        if key == '__name__':
+            raise ValueError(self._noname)
+        self._parser._validate_value_type(value)
+        return self._parser.set(self._section, key, value)
+
+    def __delitem__(self, key):
+        if key == '__name__':
+            raise ValueError(self._noname)
+        if not self._parser.has_option(self._section, key):
+            raise KeyError(key)
+        return self._parser.remove_option(self._section, key)
+
+    def __contains__(self, key):
+        if key == '__name__':
+            return False
+        return self._parser.has_option(self._section, key)
+
+    def __len__(self):
+        # __name__ is properly hidden by .options()
+        # XXX weak performance
+        return len(self._parser.options(self._section))
+
+    def __iter__(self):
+        # __name__ is properly hidden by .options()
+        # XXX weak performance
+        # XXX does not break when underlying container state changed
+        return self._parser.options(self._section).__iter__()

Lib/logging/config.py

 
 def _create_formatters(cp):
     """Create and return formatters"""
-    flist = cp.get("formatters", "keys")
+    flist = cp["formatters"]["keys"]
     if not len(flist):
         return {}
     flist = flist.split(",")
     formatters = {}
     for form in flist:
         sectname = "formatter_%s" % form
-        opts = cp.options(sectname)
-        if "format" in opts:
-            fs = cp.get(sectname, "format", 1)
-        else:
-            fs = None
-        if "datefmt" in opts:
-            dfs = cp.get(sectname, "datefmt", 1)
-        else:
-            dfs = None
+        fs = cp.get(sectname, "format", raw=True, fallback=None)
+        dfs = cp.get(sectname, "datefmt", raw=True, fallback=None)
         c = logging.Formatter
-        if "class" in opts:
-            class_name = cp.get(sectname, "class")
-            if class_name:
-                c = _resolve(class_name)
+        class_name = cp[sectname].get("class")
+        if class_name:
+            c = _resolve(class_name)
         f = c(fs, dfs)
         formatters[form] = f
     return formatters
 
 def _install_handlers(cp, formatters):
     """Install and return handlers"""
-    hlist = cp.get("handlers", "keys")
+    hlist = cp["handlers"]["keys"]
     if not len(hlist):
         return {}
     hlist = hlist.split(",")
     handlers = {}
     fixups = [] #for inter-handler references
     for hand in hlist:
-        sectname = "handler_%s" % hand
-        klass = cp.get(sectname, "class")
-        opts = cp.options(sectname)
-        if "formatter" in opts:
-            fmt = cp.get(sectname, "formatter")
-        else:
-            fmt = ""
+        section = cp["handler_%s" % hand]
+        klass = section["class"]
+        fmt = section.get("formatter", "")
         try:
             klass = eval(klass, vars(logging))
         except (AttributeError, NameError):
             klass = _resolve(klass)
-        args = cp.get(sectname, "args")
+        args = section["args"]
         args = eval(args, vars(logging))
         h = klass(*args)
-        if "level" in opts:
-            level = cp.get(sectname, "level")
+        if "level" in section:
+            level = section["level"]
             h.setLevel(logging._levelNames[level])
         if len(fmt):
             h.setFormatter(formatters[fmt])
         if issubclass(klass, logging.handlers.MemoryHandler):
-            if "target" in opts:
-                target = cp.get(sectname,"target")
-            else:
-                target = ""
+            target = section.get("target", "")
             if len(target): #the target handler may not be loaded yet, so keep for later...
                 fixups.append((h, target))
         handlers[hand] = h
     """Create and install loggers"""
 
     # configure the root first
-    llist = cp.get("loggers", "keys")
+    llist = cp["loggers"]["keys"]
     llist = llist.split(",")
     llist = list(map(lambda x: x.strip(), llist))
     llist.remove("root")
-    sectname = "logger_root"
+    section = cp["logger_root"]
     root = logging.root
     log = root
-    opts = cp.options(sectname)
-    if "level" in opts:
-        level = cp.get(sectname, "level")
+    if "level" in section:
+        level = section["level"]
         log.setLevel(logging._levelNames[level])
     for h in root.handlers[:]:
         root.removeHandler(h)
-    hlist = cp.get(sectname, "handlers")
+    hlist = section["handlers"]
     if len(hlist):
         hlist = hlist.split(",")
         hlist = _strip_spaces(hlist)
     child_loggers = []
     #now set up the new ones...
     for log in llist:
-        sectname = "logger_%s" % log
-        qn = cp.get(sectname, "qualname")
-        opts = cp.options(sectname)
-        if "propagate" in opts:
-            propagate = cp.getint(sectname, "propagate")
-        else:
-            propagate = 1
+        section = cp["logger_%s" % log]
+        qn = section["qualname"]
+        propagate = section.getint("propagate", fallback=1)
         logger = logging.getLogger(qn)
         if qn in existing:
             i = existing.index(qn)
                 child_loggers.append(existing[i])
                 i = i + 1
             existing.remove(qn)
-        if "level" in opts:
-            level = cp.get(sectname, "level")
+        if "level" in section:
+            level = section["level"]
             logger.setLevel(logging._levelNames[level])
         for h in logger.handlers[:]:
             logger.removeHandler(h)
         logger.propagate = propagate
         logger.disabled = 0
-        hlist = cp.get(sectname, "handlers")
+        hlist = section["handlers"]
         if len(hlist):
             hlist = hlist.split(",")
             hlist = _strip_spaces(hlist)

Lib/test/test_cfgparser.py

 class BasicTestCase(CfgParserTestCaseClass):
 
     def basic_test(self, cf):
-        L = cf.sections()
-        L.sort()
         E = ['Commented Bar',
              'Foo Bar',
              'Internationalized Stuff',
              'Spacey Bar From The Beginning',
              'Types',
              ]
+
         if self.allow_no_value:
             E.append('NoValue')
         E.sort()
+
+        # API access
+        L = cf.sections()
+        L.sort()
         eq = self.assertEqual
         eq(L, E)
 
+        # mapping access
+        L = [section for section in cf]
+        L.sort()
+        E.append(configparser.DEFAULTSECT)
+        E.sort()
+        eq(L, E)
+
         # The use of spaces in the section names serves as a
         # regression test for SourceForge bug #583248:
         # http://www.python.org/sf/583248
-        eq(cf.get('Foo Bar', 'foo'), 'bar')
-        eq(cf.get('Spacey Bar', 'foo'), 'bar')
-        eq(cf.get('Spacey Bar From The Beginning', 'foo'), 'bar')
+
+        # API access
+        eq(cf.get('Foo Bar', 'foo'), 'bar1')
+        eq(cf.get('Spacey Bar', 'foo'), 'bar2')
+        eq(cf.get('Spacey Bar From The Beginning', 'foo'), 'bar3')
         eq(cf.get('Spacey Bar From The Beginning', 'baz'), 'qwe')
-        eq(cf.get('Commented Bar', 'foo'), 'bar')
+        eq(cf.get('Commented Bar', 'foo'), 'bar4')
         eq(cf.get('Commented Bar', 'baz'), 'qwe')
         eq(cf.get('Spaces', 'key with spaces'), 'value')
         eq(cf.get('Spaces', 'another with spaces'), 'splat!')
         if self.allow_no_value:
             eq(cf.get('NoValue', 'option-without-value'), None)
 
-        # test vars= and default=
-        eq(cf.get('Foo Bar', 'foo', default='baz'), 'bar')
+        # test vars= and fallback=
+        eq(cf.get('Foo Bar', 'foo', fallback='baz'), 'bar1')
         eq(cf.get('Foo Bar', 'foo', vars={'foo': 'baz'}), 'baz')
         with self.assertRaises(configparser.NoSectionError):
             cf.get('No Such Foo Bar', 'foo')
         with self.assertRaises(configparser.NoOptionError):
             cf.get('Foo Bar', 'no-such-foo')
-        eq(cf.get('No Such Foo Bar', 'foo', default='baz'), 'baz')
-        eq(cf.get('Foo Bar', 'no-such-foo', default='baz'), 'baz')
-        eq(cf.get('Spacey Bar', 'foo', default=None), 'bar')
-        eq(cf.get('No Such Spacey Bar', 'foo', default=None), None)
-        eq(cf.getint('Types', 'int', default=18), 42)
-        eq(cf.getint('Types', 'no-such-int', default=18), 18)
-        eq(cf.getint('Types', 'no-such-int', default="18"), "18") # sic!
+        eq(cf.get('No Such Foo Bar', 'foo', fallback='baz'), 'baz')
+        eq(cf.get('Foo Bar', 'no-such-foo', fallback='baz'), 'baz')
+        eq(cf.get('Spacey Bar', 'foo', fallback=None), 'bar2')
+        eq(cf.get('No Such Spacey Bar', 'foo', fallback=None), None)
+        eq(cf.getint('Types', 'int', fallback=18), 42)
+        eq(cf.getint('Types', 'no-such-int', fallback=18), 18)
+        eq(cf.getint('Types', 'no-such-int', fallback="18"), "18") # sic!
         self.assertAlmostEqual(cf.getfloat('Types', 'float',
-                                           default=0.0), 0.44)
+                                           fallback=0.0), 0.44)
         self.assertAlmostEqual(cf.getfloat('Types', 'no-such-float',
-                                           default=0.0), 0.0)
-        eq(cf.getfloat('Types', 'no-such-float', default="0.0"), "0.0") # sic!
-        eq(cf.getboolean('Types', 'boolean', default=True), False)
-        eq(cf.getboolean('Types', 'no-such-boolean', default="yes"),
+                                           fallback=0.0), 0.0)
+        eq(cf.getfloat('Types', 'no-such-float', fallback="0.0"), "0.0") # sic!
+        eq(cf.getboolean('Types', 'boolean', fallback=True), False)
+        eq(cf.getboolean('Types', 'no-such-boolean', fallback="yes"),
            "yes") # sic!
-        eq(cf.getboolean('Types', 'no-such-boolean', default=True), True)
-        eq(cf.getboolean('No Such Types', 'boolean', default=True), True)
+        eq(cf.getboolean('Types', 'no-such-boolean', fallback=True), True)
+        eq(cf.getboolean('No Such Types', 'boolean', fallback=True), True)
         if self.allow_no_value:
-            eq(cf.get('NoValue', 'option-without-value', default=False), None)
+            eq(cf.get('NoValue', 'option-without-value', fallback=False), None)
             eq(cf.get('NoValue', 'no-such-option-without-value',
-                      default=False), False)
+                      fallback=False), False)
 
+        # mapping access
+        eq(cf['Foo Bar']['foo'], 'bar1')
+        eq(cf['Spacey Bar']['foo'], 'bar2')
+        eq(cf['Spacey Bar From The Beginning']['foo'], 'bar3')
+        eq(cf['Spacey Bar From The Beginning']['baz'], 'qwe')
+        eq(cf['Commented Bar']['foo'], 'bar4')
+        eq(cf['Commented Bar']['baz'], 'qwe')
+        eq(cf['Spaces']['key with spaces'], 'value')
+        eq(cf['Spaces']['another with spaces'], 'splat!')
+        eq(cf['Long Line']['foo'],
+           'this line is much, much longer than my editor\nlikes it.')
+        if self.allow_no_value:
+            eq(cf['NoValue']['option-without-value'], None)
+
+        # API access
         self.assertNotIn('__name__', cf.options("Foo Bar"),
                          '__name__ "option" should not be exposed by the API!')
 
+        # mapping access
+        self.assertNotIn('__name__', cf['Foo Bar'],
+                         '__name__ "option" should not be exposed by '
+                         'mapping protocol access')
+        self.assertFalse('__name__' in cf['Foo Bar'])
+        with self.assertRaises(ValueError):
+            cf['Foo Bar']['__name__']
+        with self.assertRaises(ValueError):
+            del cf['Foo Bar']['__name__']
+        with self.assertRaises(ValueError):
+            cf['Foo Bar']['__name__'] = "can't write to this special name"
+
         # Make sure the right things happen for remove_option();
         # added to include check for SourceForge bug #123324:
+
+        # API acceess
         self.assertTrue(cf.remove_option('Foo Bar', 'foo'),
                         "remove_option() failed to report existence of option")
         self.assertFalse(cf.has_option('Foo Bar', 'foo'),
         eq(cf.get('Long Line', 'foo'),
            'this line is much, much longer than my editor\nlikes it.')
 
+        # mapping access
+        del cf['Spacey Bar']['foo']
+        self.assertFalse('foo' in cf['Spacey Bar'])
+        with self.assertRaises(KeyError):
+            del cf['Spacey Bar']['foo']
+        with self.assertRaises(KeyError):
+            del cf['No Such Section']['foo']
+
     def test_basic(self):
         config_string = """\
 [Foo Bar]
-foo{0[0]}bar
+foo{0[0]}bar1
 [Spacey Bar]
-foo {0[0]} bar
+foo {0[0]} bar2
 [Spacey Bar From The Beginning]
-  foo {0[0]} bar
+  foo {0[0]} bar3
   baz {0[0]} qwe
 [Commented Bar]
-foo{0[1]} bar {1[1]} comment
+foo{0[1]} bar4 {1[1]} comment
 baz{0[0]}qwe {1[0]}another one
 [Long Line]
 foo{0[1]} this line is much, much longer than my editor
     def test_basic_from_dict(self):
         config = {
             "Foo Bar": {
-                "foo": "bar",
+                "foo": "bar1",
             },
             "Spacey Bar": {
-                "foo": "bar",
+                "foo": "bar2",
             },
             "Spacey Bar From The Beginning": {
-                "foo": "bar",
+                "foo": "bar3",