diff -r ffa851df0825 -r 2fb8b9db1c86 symbian-qemu-0.9.1-12/python-2.6.1/Demo/metaclasses/Meta.py --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/symbian-qemu-0.9.1-12/python-2.6.1/Demo/metaclasses/Meta.py Fri Jul 31 15:01:17 2009 +0100 @@ -0,0 +1,118 @@ +"""Generic metaclass. + +XXX This is very much a work in progress. + +""" + +import types + +class MetaMethodWrapper: + + def __init__(self, func, inst): + self.func = func + self.inst = inst + self.__name__ = self.func.__name__ + + def __call__(self, *args, **kw): + return apply(self.func, (self.inst,) + args, kw) + +class MetaHelper: + + __methodwrapper__ = MetaMethodWrapper # For derived helpers to override + + def __helperinit__(self, formalclass): + self.__formalclass__ = formalclass + + def __getattr__(self, name): + # Invoked for any attr not in the instance's __dict__ + try: + raw = self.__formalclass__.__getattr__(name) + except AttributeError: + try: + ga = self.__formalclass__.__getattr__('__usergetattr__') + except (KeyError, AttributeError): + raise AttributeError, name + return ga(self, name) + if type(raw) != types.FunctionType: + return raw + return self.__methodwrapper__(raw, self) + +class MetaClass: + + """A generic metaclass. + + This can be subclassed to implement various kinds of meta-behavior. + + """ + + __helper__ = MetaHelper # For derived metaclasses to override + + __inited = 0 + + def __init__(self, name, bases, dict): + try: + ga = dict['__getattr__'] + except KeyError: + pass + else: + dict['__usergetattr__'] = ga + del dict['__getattr__'] + self.__name__ = name + self.__bases__ = bases + self.__realdict__ = dict + self.__inited = 1 + + def __getattr__(self, name): + try: + return self.__realdict__[name] + except KeyError: + for base in self.__bases__: + try: + return base.__getattr__(name) + except AttributeError: + pass + raise AttributeError, name + + def __setattr__(self, name, value): + if not self.__inited: + self.__dict__[name] = value + else: + self.__realdict__[name] = value + + def __call__(self, *args, **kw): + inst = self.__helper__() + inst.__helperinit__(self) + try: + init = inst.__getattr__('__init__') + except AttributeError: + init = lambda: None + apply(init, args, kw) + return inst + + +Meta = MetaClass('Meta', (), {}) + + +def _test(): + class C(Meta): + def __init__(self, *args): + print "__init__, args =", args + def m1(self, x): + print "m1(x=%r)" % (x,) + print C + x = C() + print x + x.m1(12) + class D(C): + def __getattr__(self, name): + if name[:2] == '__': raise AttributeError, name + return "getattr:%s" % name + x = D() + print x.foo + print x._foo +## print x.__foo +## print x.__foo__ + + +if __name__ == '__main__': + _test()