在另一个python类中使用未绑定的方法 [英] using unbound methods in another python class

问题描述

我有一个与<unbound method foo.ops>一样的未绑定方法，我想在另一个类中使用相同的方法.举个例子

I have an unbound method as <unbound method foo.ops>, i would like to use the same method with another class. take an example

class foo2(object):
  pass

foo2.ops = foo.ops

但是

obj = foo2()
obj.ops()

raises TypeError: unbound method ops() must be called with foo instance as first argument (got nothing instead)

推荐答案

如果要将相同的方法添加到几个不相关的类中(例如，执行AOP)，请不要从其中一个中复制未绑定的方法.而是定义一个普通函数并将其作为方法分配给每个类.

If you want to add the same method to several unrelated classes (e.g. doing AOP), don't copy an unbound method from one of them. Instead, define a plain function and assign it as a method to every class.

通常，更好的方法是mixin(使用纯继承)或元类(类装饰器语法简洁).

Usually a better way to do it is a mixin (using plain inheritance) or a metaclass (class decorator syntax is neat).

如果您很想从类中窃取某个方法(例如，您无法控制的方法)，则可以从未绑定方法"包装器中提取该方法:foo2.ops.im_func;这是一个简单的函数，您可以将其作为方法分配给另一个类.

If you're hell-bound to steal a method from a class (e.g. one you don't control), you can extract it from the 'unbound method' wrapper: foo2.ops.im_func; it's a plain function and you can assign it as a method to another class.

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