元类将类名作为参数传递

Question

我有元class喜欢：

class Metaclass(type):
    def __new__(self, name, bases, attrs):

        for k, v in attrs.iteritems():
            if isinstance(v, types.FunctionType):
               attrs[k] = self.decorator(v)
        return super(MetaClass, self).__new__(self, name, bases, attrs)

    @classmethod
    def decorator(cls, func):
        def wrapper(*args, **kwargs):
            print(func.__name__)

但我无法得到 func.__class__.__name__ 它打印 metaclass。我想获取 func.__name__ 的 class 的名称。显然这是不可能的 python 2.7(?) 我可以将 classname 作为参数传递吗？对于调用此装饰器的方法？即如果 testmethod 调用 metaclass 装饰器并传递 Testclass 作为参数。所以如果我知道 func.__name__ 来自特定的 class 做特定的事情。

Answer 1

您忘记 return 装饰器的包装器。应该是：

class Metaclass(type):
    def __new__(self, name, bases, attrs):

        for k, v in attrs.iteritems():
            if isinstance(v, types.FunctionType):
               attrs[k] = self.decorator(v)
        return super(Metaclass, self).__new__(self, name, bases, attrs)

    @classmethod
    def decorator(cls, func):
        def wrapper(*args, **kwargs):
            print(func.__name__)
        return wrapper

您现在可以使用元class:

>>> class TestClass(object):
    __metaclass__ = Metaclass
    def foo(self):
        return "bar"

>>> t = TestClass()
>>> x = t.foo()
foo
>>> print x
None

该方法已被包装器正确替换。

在您之前（现已删除）的问题中，您要求 print "this method is from Testclass"。您可以简单地将 class 名称传递给装饰器：

class Metaclass(type):
    def __new__(self, name, bases, attrs):

        for k, v in attrs.iteritems():
            if isinstance(v, types.FunctionType):
               attrs[k] = self.decorator(v, name)
        return super(Metaclass, self).__new__(self, name, bases, attrs)

    @classmethod
    def decorator(cls, func, name):
        def wrapper(self, *args, **kwargs):
            print "%s defined in %s called from %s instance" % (func.__name__,
                name, self.__class__.__name__)
            return func(self, *args, **kwargs)
        return wrapper

您现在获得：

>>> class TestClass(object):
    __metaclass__ = Metaclass
    def foo(self):
        return "bar"


>>> t = TestClass()
>>> x = t.foo()
foo defined in TestClass called from TestClass instance
>>> print x
bar

元类将类名作为参数传递

Metaclass pass classname as parameter

python

metaclass

python-2.7