#!/usr/bin/env python
def enum(*names):
"""A true immutable symbolic enumeration with qualified value access."""
class EnumValue(object):
__slots__ = ("type", "value",)
def __init__(self, type, value):
self.type = type
self.value = value
def __hash__(self):
return hash(self.value)
def __cmp__(self, other):
return cmp(self.value, other.value)
def __invert__(self):
return self.type.values[(len(self.type) - 1) - self.value]
def __nonzero__(self):
return bool(self.value)
def __repr__(self):
return str(self.type.names[self.value])
class EnumClass(object):
__slots__ = ("names", "mapping", "values",)
def __init__(self, *names):
self.names = names
self.values = dict(
(i, EnumValue(self, i)) for i in range(len(names))
)
self.mapping = dict(
(names[i], value) for i, value in self.values.items()
)
def __getattr__(self, attr):
try:
return self.mapping[attr]
except KeyError:
raise AttributeError(attr)
def __iter__(self):
return iter(self.values.values())
def __len__(self):
return len(self.values)
def __getitem__(self, i):
return self.values[i]
def __repr__(self):
return "<Enum {0:s}>".format(str(self.names))
def __str__(self):
return "enum {0:s}".format(str(self.values))
return EnumClass(*names)
Days = enum("Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat")
print Days
print Days.Mon
print Days.Fri
print Days.Mon < Days.Fri
print list(Days)
for day in Days:
print "Day: {0:s}".format(repr(day))
Confirmation = enum("No", "Yes")
answer = Confirmation.No
print "Your answer is not", ~answer
