Python类修饰器将元素访问转换为属性访问 [英] Python class decorator converting element access to attribute access

问题描述

我正在寻找Python类的装饰器，该装饰器会将任何元素访问转换为属性访问，如下所示：

I'm looking for a decorator for Python class that would convert any element access to attribute access, something like this:

@DictAccess
class foo(bar):
    x = 1
    y = 2

myfoo = foo()
print myfoo.x # gives 1
print myfoo['y'] # gives 2
myfoo['z'] = 3
print myfoo.z # gives 3

这样的装饰器是否已经存在？如果没有，实施它的正确方法是什么？我应该将 __ new __ 包装在类 foo 上并添加 __ getitem __ 并实例的 __ setitem __ 属性？那么如何使它们正确地绑定到新类上呢？我知道 DictMixin 可以帮助我支持所有 dict 功能，但是我仍然必须在类中获得基本方法不知何故。

Does such decorator exist somewhere already? If not, what is the proper way to implement it? Should I wrap __new__ on class foo and add __getitem__ and __setitem__ properties to the instance? How make these properly bound to the new class then? I understand that DictMixin can help me support all dict capabilities, but I still have to get the basic methods in the classes somehow.

推荐答案

装饰器需要添加 __ getitem __ 方法和 __ setitem __ 方法：

The decorator needs to add a __getitem__ method and a __setitem__ method:

def DictAccess(kls):
    kls.__getitem__ = lambda self, attr: getattr(self, attr)
    kls.__setitem__ = lambda self, attr, value: setattr(self, attr, value)
    return kls

这将适合您的示例代码：

That will work fine with your example code:

class bar:
    pass

@DictAccess
class foo(bar):
    x = 1
    y = 2

myfoo = foo()
print myfoo.x # gives 1
print myfoo['y'] # gives 2
myfoo['z'] = 3
print myfoo.z # gives 3

该测试代码产生期望值：

That test code produces the expected values:

1
2
3

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