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Advanced Enumerations (compatible with Python's stdlib Enum), NamedTuples, and NamedConstants

Project description

aenum --- support for advanced enumerations, namedtuples, and constants

aenum includes the new Python stdlib enum module available in Python 3.4
backported for previous versions of Python from 2.7 and 3.3+
tested on 2.7, and 3.3+

An ``Enum`` is a set of symbolic names (members) bound to unique, constant
values. Within an enumeration, the members can be compared by identity, and
the enumeration itself can be iterated over.

A ``NamedTuple`` is a class-based, fixed-length tuple with a name for each
possible position accessible using attribute-access notation.

A ``NamedConstant`` is a class whose members cannot be rebound; it lacks all other
``Enum`` capabilities, however; consequently, it can have duplicate values.
There is also a ``module`` function that can insert the ``NamedConstant`` class
into ``sys.modules`` where it will appear to be a module whose top-level
names cannot be rebound.

Module Contents

Base class for ``creating NamedTuples``_, either by subclassing or via it's
functional API.

NamedConstant class for creating groups of constants. These names cannot be rebound
to other values.

Base class for creating enumerated constants. See section ``Enum Functional API``_
for an alternate construction syntax.

Base class for creating enumerated constants that are also subclasses of ``int``.

Derived class that automatically assigns an ``int`` value to each member.

Derived class that adds ``<``, ``<=``, ``>=``, and ``>`` methods to an ``Enum``.

Derived class that ensures only one name is bound to any one value.

Enum class decorator that ensures only one name is bound to any one value.

Descriptor to add constant values to an ``Enum``

Helper to transform target global variables into an ``Enum``.

Helper for specifying keyword arguments when creating ``Enum`` members.

Helper for inserting ``Enum`` members into a namespace (usually ``globals()``.

Helper for adding new ``Enum`` members after creation.

Function to take a ``NamedConstant`` or ``Enum`` class and insert it into
``sys.modules`` with the affect of a module whose top-level constant and
member names cannot be rebound.

Descriptor to add a normal (non-``Enum`` member) attribute to an ``Enum``
or ``NamedConstant``.

Creating an Enum

Enumerations can be created using the ``class`` syntax, which makes them
easy to read and write. To define an enumeration, subclass ``Enum`` as

>>> from aenum import Enum
>>> class Color(Enum):
... red = 1
... green = 2
... blue = 3

The ``Enum`` class is also callable, providing the following functional API::

>>> Animal = Enum('Animal', 'ant bee cat dog')
>>> Animal
<enum 'Animal'>
>>> Animal.ant
<Animal.ant: 1>
>>> Animal.ant.value
>>> list(Animal)
[<Animal.ant: 1>, <Animal.bee: 2>, < 3>, < 4>]

Creating NamedTuples


The most common way to create a new NamedTuple will be via the functional API::

>>> from aenum import NamedTuple
>>> Book = NamedTuple('Book', 'title author genre', module=__name__)


The simple method of creating ``NamedTuples`` requires always specifying all
possible arguments when creating instances; failure to do so will raise

However, it is possible to specify both docstrings and default values when
creating a ``NamedTuple`` using the class method::

>>> class Point(NamedTuple):
... x = 0, 'horizontal coordinate', 0
... y = 1, 'vertical coordinate', 0
>>> Point()
Point(x=0, y=0)

Creating NamedConstants

>>> class K(NamedConstant):
... PI = 3.141596
... TAU = 2 * PI
>>> K.TAU

Project details

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