Enumeration types for Python
Ever find yourself juggling constants, wondering whether the value 0x002A
originated as the index to the Comments field or as the protocol version
number from that binary file? The enums module is a simple implementation
of named enumeration types for Python. It is useful for avoiding lots of
globally defined constants that don't remember who they are or where they
came from. With enums, you can define a collection of values as having a
common type and behavior, and the values will remember their original names
and types.
To use enums, define an enumeration class that inherits from Enum, and then
assign values within the class's scope as Const instances. Then call the
close() class method for your enumeration class, and all the Const values
will be converted in-place to unique instances of your enumeration type. If
you want to control the initialization of your enumeration class, define an
__init__ method just as you would for any normal class, and pass the
arguments to Const(). The arguments will be passed on to your __init__
class unchanged.
The enums module also provides a Registry class, which allows multiple
owners to safely reserve name/value pairs within a shared space.
Example usage:
>>> from enums import Enum, Const
>>> class Enumeration(Enum):
>>> VALUE1 = Const()
>>> VALUE2 = Const()
>>> Enumeration.close()
>>> class Enumeration2(Enum):
>>> def __init__(self, int_val):
>>> assert isinstance(int_val, int)
>>> self._int_val = int_val
>>> super(Enumeration2, self).__init__(int_val)
>>> def __int__(self):
>>> return self._int_val
>>> VALUE1 = Const(10)
>>> VALUE2 = Const(100)
>>> VALUE3 = Const(1000)
>>> Enumeration2.close()
>>> Enumeration.VALUE1
Enumeration.VALUE1
>>> Enumeration.VALUE2
Enumeration.VALUE2
>>> Enumeration.VALUE1 == Enumeration.VALUE2
False
>>> Enumeration.VALUE1 == Enumeration2.VALUE1
False
>>> isinstance(Enumeration.VALUE1, Enumeration)
True
>>> int(Enumeration2.VALUE3)
1000