diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Demo/newmetaclasses/Enum.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Demo/newmetaclasses/Enum.py Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,177 @@ +"""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 + +class FullEnum: + __metaclass__ = FullEnumMetaclass + +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()