Question

下面的脚本试图从类Inner1中删除Outer嵌套类。我收到明确的错误“ TypeError：无法删除__class__属性”。死胡同？

def Loader(cls):
    for key in dir(cls):
        value = getattr(cls, key)
        if isinstance(value, type):
            delattr(cls, key)
    return cls

@Loader
class Outer:
    class Inner1:
        X = 1

print(Outer.Inner1.X)

Answer 1

问题是以下行：

if isinstance(value, type):

匹配从type继承的所有内容。如果您只希望删除在装饰类中显式定义的内部类，则可以使用以下内容：

from inspect import isclass

def Loader(cls):
    # vars returns the __dict__ attributes, so only names that are explicitely defined in cls.
    for key, value in vars(cls).copy().items():

        # If it is a class, delete it
        if isclass(value):
            delattr(cls, key)

    return cls

@Loader
class Outer:
    class Inner1:
        X = 1

print(Outer.Inner1.X) # AttributeError: type object 'Outer' has no attribute 'Inner1'

另一种选择是使装饰器成为一个类，并明确告诉您要删除的名称。例如

class Loader:
    def __init__(self, *args):
        # Store the given names to delete
        self.names = args

    def __call__(self, cls):
        for name in self.names:
            try:
                delattr(cls, name)
            except AttributeError:
                pass

        return cls

@Loader('Inner1', 'Inner2', 'etc')
class Outer:
    class Inner1:
        X = 1

print(Outer.Inner1.X) # AttributeError: type object 'Outer' has no attribute 'Inner1'

也就是说，我不确定为什么要装饰一个类并定义要动态删除的内部类……为什么不……根本不定义它们？：D

有什么办法可以删除Python中的嵌套类？

1 个答案: