Metadata-Version: 1.0
Name: recordtype
Version: 1.1
Summary: Similar to namedtuple, but instances are mutable.
Home-page: https://bitbucket.org/ericvsmith/recordtype
Author: Eric V. Smith
Author-email: eric@trueblade.com
License: Apache License Version 2.0
Description: ===========
        recordtype
        ===========
        
        Overview
        ========
        
        recordtype provides a factory function, named
        recordtype.recordtype. It is similar to collections.namedtuple, with
        the following differences:
        
        * recordtype instances are mutable.
        
        * recordtype supports per-field default values.
        
        * recordtype supports an optional default value, to be used by all
          fields do not have an explicit default value.
        
        Typical usage
        =============
        
        You can use recordtype like a mutable namedtuple::
        
            from recordtype import recordtype
        
            Point = recordtype('Point', 'x y')
            p = Point(1, 3)
            p.x = 2
            assert p.x == 2
            assert p.y == 3
        
        Or, you can specify a default value for all fields::
        
            Point = recordtype('Point', 'x y', default=3)
            p = Point(y=2)
            assert p.x == 3
            assert p.y == 2
        
        Or, you can specify per-field default values::
        
            Point = recordtype('Point', [('x', 0), ('y', 100)])
            p = Point()
            assert p.x == 0
            assert p.y == 100
        
        You can also specify a the per-field defaults with a mapping, instead
        of an interable. Note that this is only useful with an ordered
        mapping, such as an OrderedDict::
        
            from collections import OrderedDict
            Point = recordtype('Point', OrderedDict((('y', 0),
                                                     ('x', 100))))
            p = Point()
            assert p.x == 100
            assert p.y == 0
        
        The default value will only be used if it is provided and a per-field
        default is not used::
        
            Point = recordtype('Point', ['x', ('y', 100)], default=10)
            p = Point()
            assert p.x == 10
            assert p.y == 100
        
        If you use a mapping, the value NO_DEFAULT is convenient to specify
        that a field uses the default value::
        
            from recordtype import NO_DEFAULT
            Point = recordtype('Point', OrderedDict((('y', NO_DEFAULT),
                                                     ('x', 100))),
                                        default=5)
            p = Point()
            assert p.x == 100
            assert p.y == 5
        
        
        Creating types
        --------------
        
        Specifying Fields
        =================
        
        Fields can be specified as in namedtuple: as either a string specifing
        the field names, or as a iterable of field names. These two uses are
        equivalent::
        
            Point = recordtype('Point', 'x y')
            Point = recordtype('Point', ['x', 'y'])
        
        If using a string, commas are first converted to spaces. So these are
        equivalent::
        
            Point = recordtype('Point', 'x y')
            Point = recordtype('Point', 'x,y')
        
        
        Specifying Defaults
        ===================
        
        Per-field defaults can be specified by supplying a 2-tuple (name,
        default_value) instead of just a string for the field name. This is
        only supported when you specify a list of field names::
        
            Point = recordtype('Point', [('x', 0), ('y', 0)])
            p = Point(3)
            assert p.x == 3
            assert p.y == 0
        
        In addition to, or instead of, these per-field defaults, you can also
        specify a default value which is used when no per-field default value
        is specified::
        
            Point = recordtype('Point', 'x y z', default=0)
            p = Point(y=3)
            assert p.x == 0
            assert p.y == 3
            assert p.z == 0
        
            Point = recordtype('Point', [('x', 0), 'y', ('z', 0)], default=4)
            p = Point(z=2)
            assert p.x == 0
            assert p.y == 4
            assert p.z == 2
        
        In addition to supplying the field names as an iterable of 2-tuples,
        you can also specify a mapping. The keys will be the field names, and
        the values will be the per-field default values. This is most useful
        with an OrderedDict, as the order of the fields will then be
        deterministic.  The module variable NO_DEFAULT can be specified if you
        want a field to use the per-type default value instead of specifying
        it with a field::
        
            Point = recordtype('Point', OrderedDict((('x', 0),
                                                     ('y', NO_DEFAULT),
                                                     ('z', 0),
                                                     )),
                                        default=4)
            p = Point(z=2)
            assert p.x == 0
            assert p.y == 4
            assert p.z == 2
        
        Writing to values
        =================
        
        The objects retured by the factory function are fully writable, unlike
        the tuple-derived classes returned by namedtuple::
        
            Point = recordtype('Point', 'x y')
            p = Point(1, 2)
            p.y = 4
            assert p.x == 1
            assert p.y == 4
        
        
        Specifying __slots__
        ====================
        
        By default, the returned class sets __slots__, which is initialized to
        the field names. While this decreases memory usage by eliminating the
        instance dict, it also means that you cannot create new instance
        members.
        
        To change this behavior, specify use_slots=False when creating the
        recordtype::
        
            Point = recordtype('Point', 'x y', use_slots=False)
            p = Point(0, 1)
            p.z = 2
            assert p.x == 0
            assert p.y == 1
            assert p.z == 2
        
        
        Additional class members
        ========================
        
        recordtype classes contain these members:
        
        * _asdict(): Returns a dict which maps field names to their
          corresponding values.
        
        * _source: A string with the pure Python source code used to create
          the recordtype class. The source makes the recordtype
          self-documenting. It can be printed, executed using exec(), or saved
          to a file and imported.
        
        * _fields: Tuple of strings listing the field names. Useful for introspection.
        
        
        Renaming invalid field names
        ============================
        
        This functionality is identical to namedtuple. If you specify
        rename=True, then any invalid field names are changed to _0, _1,
        etc. Reasons for a field name to be invalid are:
        
        * Zero length strings.
        
        * Containing characters other than alphanumerics and underscores.
        
        * A conflict with a Python reserved identifier.
        
        * Beginning with a digit.
        
        * Beginning with an underscore.
        
        * Using the same field name more than once.
        
        For example::
        
            Point = recordtype('Point', 'x x for', rename=True)
            assert Point._fields == ('x', '_1', '_2')
        
        
        Creating and using instances
        ----------------------------
        
        Because the type returned by recordtype is a normal Python class, you
        create instances as you would with any Python class.
        
        
        Change log
        ==========
        
        1.1 2011-11-14 Eric V. Smith
        ----------------------------
        * No API or code changes.
        * Fixed project URL in setup.py.
        * Fixed license description in setup.py.
        
        1.0 2011-10-23 Eric V. Smith
        ----------------------------
        * Stabilize API, move to version 1.0.
        * Added "python setup.py test" support to run unittests.
        * Improve documentation examples.
        * Renamed "default_default" to just "default".
        * Expose "NO_DEFAULT".
        * Support mapping objects in addition to strings and lists for field_names.
        * Add tests for iterables, not just lists, for field_names.
        
        0.2 2011-10-13 Eric V. Smith
        ----------------------------
        * Fix a typo in the documentation, no code changes.
        
        0.1 2011-10-12 Eric V. Smith
        ----------------------------
        * Initial release.
        
Platform: UNKNOWN
Classifier: Development Status :: 5 - Production/Stable
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: Apache Software License
Classifier: Topic :: Software Development :: Libraries :: Python Modules
Classifier: Programming Language :: Python :: 2.6
Classifier: Programming Language :: Python :: 2.7
