metaclass作用？以及应用场景？

“`” metaclass用来指定类是由谁创建的。

类的metaclass 默认是type。我们也可以指定类的metaclass值。在python3中

<pre><code>class MyType(type):
def __call__(self, *args, **kwargs):
return 'MyType'

class Foo(object, metaclass=MyType):
def __init__(self):
return 'init'

def __new__(cls, *args, **kwargs):
return cls.__init__(cls)

def __call__(self, *args, **kwargs):
return 'call'

obj = Foo()
print(obj) # MyType
</code></pre>

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<pre><code> "“`