动态地向类添加装饰器 [英] Dynamically add a decorator to class

问题描述

我有一个相当大且涉及广泛的装饰器，用于调试要动态添加的PyQt信号上课。有没有办法动态地向类添加装饰器？

I have a rather large and involved decorator to debug PyQt signals that I want to dynamically add to a class. Is there a way to add a decorator to a class dynamically?

我可能是从错误的角度解决了这个问题，所以这就是我要完成的工作。

I might be approaching this problem from the wrong angle, so here is what I want to accomplish.

1. 我有一个装饰器，可以发现/附加所有pyqt信号


2. 此装饰器非常适合调试单个类的信号。但是，有时候我想附加到应用程序中的所有信号上。


3. 我想将此装饰器动态地附加到我所有有信号的类上。

可能的解决方案/想法

到目前为止，我已经考虑过几种可能的解决方案：

Possible solutions/ideas

I've thought through a few possible solutions so far:

1. 继承：如果我所有的类都具有相同的基类（Python内置的除外），这将很容易。对象和PyQt内置的 QtCore.QObject ）。我想我可以将这个装饰器附加到我的基础班上，一切都会按预期进行。但是，在此特定应用程序中不是这种情况。我也不想将所有类都更改为具有相同的基类。


2. 猴子补丁Python object 或 QtCore.QObject ：我不知道这实际上如何工作。但是，从理论上讲，我可以将这些基类之一 __ init __ 更改为我在装饰器中定义的 new_init 吗？这似乎真的很危险而且很骇人，但是也许这是一种好方式？


3. 元类：我认为元类在这种情况下不起作用，因为我不得不动态地将 __ metaclass __ 属性添加到我想将装饰器注入的类中。我认为这是不可能的，因为插入该属性必须已经构造了类。因此，我定义的任何元类都不会被调用。这是真的？

1. Inheritance: This would be easy if all my classes had the same base class (other than Python's built-in object and PyQt's built-in QtCore.QObject). I suppose I could just attach this decorator to my base class and everything would workout as expected. However, this is not the case in this particular application. I don't want to change all my classes to have the same base class either.
2. Monkey-patch Python object or QtCore.QObject: I don't know how this would work practically. However, in theory could I change one of these base classes' __init__ to be the new_init I define in my decorator? This seems really dangerous and hackish but maybe it's a good way?
3. Metaclasses: I don't think metaclasses will work in this scenario because I'd have to dynamically add the __metaclass__ attribute to the classes I want to inject the decorator into. I think this is impossible because to insert this attribute the class must have already been constructed. Thus, whatever metaclass I define won't be called. Is this true?

我尝试了几种元类魔术的变体，但似乎没有任何效果。我觉得使用元类可能是完成我想要的事情的一种方法，但是我似乎无法使其正常工作。

I tried a few variants of metaclass magic but nothing seemed to work. I feel like using metaclasses might be a way to accomplish what I want, but I can't seem to get it working.

再次，我可能会考虑所有这些错误。本质上，我想将上面引用的装饰器中的行为附加到应用程序中的所有类（甚至可能是选择类的列表）。另外，如有必要，我可以重构我的装饰器。我不太在乎是否将此行为附加到装饰器或其他机制上。我只是假设此装饰器已经完成了我希望为单个类完成的工作，因此可能很容易扩展。

Again, I might be going about this all wrong. Essentially I want to attach the behavior in my decorator referenced above to all classes in my application (maybe even a list of select classes). Also, I could refactor my decorator if necessary. I don't really care if I attach this behavior with a decorator or another mechanism. I just assumed this decorator already accomplishes what I want for a single class so maybe it was easy to extend.

推荐答案

装饰器无济于事超过自动应用的可调用项。要手动应用它，请用装饰器的返回值替换该类：

Decorators are nothing more than callables that are applied automatically. To apply it manually, replace the class with the return value of the decorator:

import somemodule

somemodule.someclass = debug_signals(somemodule.someclass)

这将替换 somemodule。 someclass 名称，返回值为 debug_signals ，我们通过了原始的 somemodule.someclass 课。

This replaces the somemodule.someclass name with the return value of debug_signals, which we passed the original somemodule.someclass class.

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