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v0.5.1
v0.5.1
https://github.com/python/cpython
Tip revision: 85420413f89fba7acd890a1b19ca566c81e93f67 authored by Georg Brandl on 31 July 2010, 12:06:51 UTC
From Martin: New UUIDs for the 3.2 release series.
From Martin: New UUIDs for the 3.2 release series.
Tip revision: 8542041
Enum.py
"""Enumeration metaclass."""
class EnumMetaclass(type):
"""Metaclass for enumeration.
To define your own enumeration, do something like
class Color(Enum):
red = 1
green = 2
blue = 3
Now, Color.red, Color.green and Color.blue behave totally
different: they are enumerated values, not integers.
Enumerations cannot be instantiated; however they can be
subclassed.
"""
def __init__(cls, name, bases, dict):
super(EnumMetaclass, cls).__init__(name, bases, dict)
cls._members = []
for attr in dict.keys():
if not (attr.startswith('__') and attr.endswith('__')):
enumval = EnumInstance(name, attr, dict[attr])
setattr(cls, attr, enumval)
cls._members.append(attr)
def __getattr__(cls, name):
if name == "__members__":
return cls._members
raise AttributeError(name)
def __repr__(cls):
s1 = s2 = ""
enumbases = [base.__name__ for base in cls.__bases__
if isinstance(base, EnumMetaclass) and not base is Enum]
if enumbases:
s1 = "(%s)" % ", ".join(enumbases)
enumvalues = ["%s: %d" % (val, getattr(cls, val))
for val in cls._members]
if enumvalues:
s2 = ": {%s}" % ", ".join(enumvalues)
return "%s%s%s" % (cls.__name__, s1, s2)
class FullEnumMetaclass(EnumMetaclass):
"""Metaclass for full enumerations.
A full enumeration displays all the values defined in base classes.
"""
def __init__(cls, name, bases, dict):
super(FullEnumMetaclass, cls).__init__(name, bases, dict)
for obj in cls.__mro__:
if isinstance(obj, EnumMetaclass):
for attr in obj._members:
# XXX inefficient
if not attr in cls._members:
cls._members.append(attr)
class EnumInstance(int):
"""Class to represent an enumeration value.
EnumInstance('Color', 'red', 12) prints as 'Color.red' and behaves
like the integer 12 when compared, but doesn't support arithmetic.
XXX Should it record the actual enumeration rather than just its
name?
"""
def __new__(cls, classname, enumname, value):
return int.__new__(cls, value)
def __init__(self, classname, enumname, value):
self.__classname = classname
self.__enumname = enumname
def __repr__(self):
return "EnumInstance(%s, %s, %d)" % (self.__classname, self.__enumname,
self)
def __str__(self):
return "%s.%s" % (self.__classname, self.__enumname)
class Enum(metaclass=EnumMetaclass):
pass
class FullEnum(metaclass=FullEnumMetaclass):
pass
def _test():
class Color(Enum):
red = 1
green = 2
blue = 3
print(Color.red)
print(repr(Color.red))
print(Color.red == Color.red)
print(Color.red == Color.blue)
print(Color.red == 1)
print(Color.red == 2)
class ExtendedColor(Color):
white = 0
orange = 4
yellow = 5
purple = 6
black = 7
print(ExtendedColor.orange)
print(ExtendedColor.red)
print(Color.red == ExtendedColor.red)
class OtherColor(Enum):
white = 4
blue = 5
class MergedColor(Color, OtherColor):
pass
print(MergedColor.red)
print(MergedColor.white)
print(Color)
print(ExtendedColor)
print(OtherColor)
print(MergedColor)
def _test2():
class Color(FullEnum):
red = 1
green = 2
blue = 3
print(Color.red)
print(repr(Color.red))
print(Color.red == Color.red)
print(Color.red == Color.blue)
print(Color.red == 1)
print(Color.red == 2)
class ExtendedColor(Color):
white = 0
orange = 4
yellow = 5
purple = 6
black = 7
print(ExtendedColor.orange)
print(ExtendedColor.red)
print(Color.red == ExtendedColor.red)
class OtherColor(FullEnum):
white = 4
blue = 5
class MergedColor(Color, OtherColor):
pass
print(MergedColor.red)
print(MergedColor.white)
print(Color)
print(ExtendedColor)
print(OtherColor)
print(MergedColor)
if __name__ == '__main__':
_test()
_test2()