initial import

--HG--
branch : aspn

src/enum.py

@@ -0,0 +1,52 @@
+def Enum(*names):
+   ##assert names, "Empty enums are not supported" # <- Don't like empty enums? Uncomment!
+
+   class EnumClass(object):
+      __slots__ = names
+      def __iter__(self):        return iter(constants)
+      def __len__(self):         return len(constants)
+      def __getitem__(self, i):  return constants[i]
+      def __repr__(self):        return 'Enum' + str(names)
+      def __str__(self):         return 'enum ' + str(constants)
+
+   class EnumValue(object):
+      __slots__ = ('__value')
+      def __init__(self, value): self.__value = value
+      Value = property(lambda self: self.__value)
+      EnumType = property(lambda self: EnumType)
+      def __hash__(self):        return hash(self.__value)
+      def __cmp__(self, other):
+         # C fans might want to remove the following assertion
+         # to make all enums comparable by ordinal value {;))
+         assert self.EnumType is other.EnumType, "Only values from the same enum are comparable"
+         return cmp(self.__value, other.__value)
+      def __invert__(self):      return constants[maximum - self.__value]
+      def __nonzero__(self):     return bool(self.__value)
+      def __repr__(self):        return str(names[self.__value])
+
+   maximum = len(names) - 1
+   constants = [None] * len(names)
+   for i, each in enumerate(names):
+      val = EnumValue(i)
+      setattr(EnumClass, each, val)
+      constants[i] = val
+   constants = tuple(constants)
+   EnumType = EnumClass()
+   return EnumType
+
+
+if __name__ == '__main__':
+   print '\n*** Enum Demo ***'
+   print '--- Days of week ---'
+   Days = Enum('Mo', 'Tu', 'We', 'Th', 'Fr', 'Sa', 'Su')
+   print Days
+   print Days.Mo
+   print Days.Fr
+   print Days.Mo < Days.Fr
+   print list(Days)
+   for each in Days:
+      print 'Day:', each
+   print '--- Yes/No ---'
+   Confirmation = Enum('No', 'Yes')
+   answer = Confirmation.No
+   print 'Your answer is not', ~answer