如何为类本身（而不是类的实例）选择自定义字符串表示形式？

考虑这个类：

class foo(object):
    pass

默认的字符串表示形式如下所示：

>>> str(foo)
"<class '__main__.foo'>"

如何使其显示自定义字符串？

_{See How to print instances of a class using print()? https://stackoverflow.com/questions/1535327 for the corresponding question about instances of the class.}

_{In fact, this question is really a special case of that one - because in Python, classes are themselves also objects belonging to their own class - but it's not directly obvious how to apply the advice, since the default "class of classes" is pre-defined.}

实施__str__() https://docs.python.org/3/reference/datamodel.html#object.__str__ or __repr__() https://docs.python.org/3/reference/datamodel.html#object.__repr__在类的元类中。

class MC(type):
  def __repr__(self):
    return 'Wahaha!'

class C(object):
  __metaclass__ = MC

print(C)

Use __str__如果您的意思是可读的字符串化，请使用__repr__以获得明确的表述。

编辑：Python 3 版本

class MC(type):
  def __repr__(self):
    return 'Wahaha!'

class C(object, metaclass=MC):
    pass


print(C)