__decorated__为Python装饰 [英] __decorated__ for python decorators

问题描述

由于2.4（2.6类），Python允许你来装点使用其他功能的功能：

As of 2.4 (2.6 for classes), python allows you to decorate a function with another function:

def d(func): return func

@d
def test(first): pass

这是一个方便的语法糖。你可以做各种装饰用的东西整齐而不做一个烂摊子。但是，如果你想找出得到装饰你赴汤蹈火原有的功能（如 Cls.method .__ FUNC __.__封闭__ [0] .cell_contents 或更糟）

我发现自己希望一个更好的方式，发现曾有过关于添加了一个名为变量有关python-dev的一些讨论 __装饰__ 来返回的[新]功能装饰。然而，似乎没有去任何地方。

I found myself wishing for a better way and found that there had been some discussion on python-dev about adding a variable called __decorated__ to the [new] function returned by the decorator. However, it appears that didn't go anywhere.

作为一个敢于冒险的人，以及有过了大约4年pretty重蟒蛇的经验，我想我会考虑在Python编译器的源实施 __装饰__ ，只是为了看看是怎么回事。

Being an adventuresome person, and having had pretty heavy python experience for about 4 years, I thought I would look into implementing __decorated__ in the python compiler source, just to see how it goes.

说实话，我从来没有钻研的引擎盖下的C，所以我的第一个小时，一直只是试图让底层C code ++工程的意义。所以，首先什么是最好的资源来让我的头围绕什么，我将不得不改变/添加对 __装饰__ ？

To be honest I have never delved into the C underneath the hood, so my first hours have been just trying to make sense of how the underlying C code works. So firstly, what would be the best resources to get my head around what I would have to change/add for __decorator__?

其次，如果一个装饰返回一个新的功能，那么 __ __装饰将只返回原始的，装饰的功能。但是，如果装饰返回原有的功能，会发生什么？下面是我能想到的三个选项（第三个是我的最爱）：

Secondly, if a decorator returns a new function then __decorated__ would just return the original, decorated function. However, if the decorator returns the original function, what should happen? Here are three options I could think of (the third is my favorite):

1. 请不要添加 __ __装饰。


2. 添加 __ __装饰，但它设置为无。


3. 添加 __ __装饰并将其设置为原有的功能呢。

1. Don't add __decorator__.
2. Add __decorator__ but set it to None.
3. Add __decorator__ and set it to the original function anyway.

因此​​，如果发生这种情况，你觉得什么是最好的选择吗？

So if it were to happen, what do you think would be the best option?

更新：

别人<一个href=\"http://stackoverflow.com/questions/3375573/finding-a-functions-parameters-in-python/3501316#3501316\">brought我注意了的我错过了一个场景。当装饰既不返回原有的功能，也不是包装了原来的功能，会发生什么？在这一点上没有什么是抱着原来的函数的引用，它会得到垃圾收集。 （感谢 Oddthinking ！）

Someone else brought to my attention a scenario that I had missed. What happens when the decorator returns neither the original function nor a function that wraps the original? At that point nothing is holding a reference to the original function and it will get garbage collected. (Thanks Oddthinking!)

因此​​，在这种情况下，我认为我会仍与第三个选项去。由装饰返回的对象将获得引用原函数__ __装饰名称。这意味着它不会被垃圾回收。

So in that case, I think that I would still go with the third option. The object returned by the decorator would gain a __decorated__ name that references the original function. This would mean that it would not be garbage-collected.

这似乎不可思议，我认为从一个类定义的函数将完全消失，因为你装饰它。在我的脑海里，甚至是更有理由有一个 __ __装饰属性适用于每一个装饰。然而，它更可能是我的直觉是错误的，而目前的行为是大多数人所期望的。 有什么想法？

It seems weird to me that the function from a class definition would utterly disappear because you decorated it. In my mind that is even more reason to have a __decorated__ attribute applied for every decorator. However, it's more likely that my intuition is faulty and that the current behavior is what most people would expect. Any thoughts?

P.S。这是早期，更普遍的一个扩展<一个href=\"http://stackoverflow.com/questions/3375573/finding-a-functions-parameters-in-python\">question我有。我也去了解更多信息与一个<一个第一部分href=\"http://stackoverflow.com/questions/3505029/extending-the-$c$c-of-python-adding-language-features\">separate帖子。

p.s. this is an extension of an earlier, more general question I had. I also went for more info on the first part with a separate post.

推荐答案

好了，独立了，这是否是一个好主意任何讨论的，我会去的选项＃3，因为它是最一致的：它总是表明，功能已经由属性的presence装饰，访问属性的值总是返回功能，所以您不必对它进行测试对无

Well, independent of any discussion over whether this is a good idea, I'd go for option #3 because it's the most consistent: it always shows that the function has been decorated by the presence of the attribute, and accessing the value of the attribute always returns a function, so you don't have to test it against None.

您也应该考虑这一点，虽然：你会建议做一下手工装饰？例如。

You should also consider this, though: what would you propose to do about manual decoration? e.g.

def test(first): pass
test = d(test)

就问题的第一部分，我没有看过Python的跨preTER源$ C ​​$ C非常多，所以我就没法给你指出什么特别有用。

Regarding the first part of the question, I haven't looked at the Python interpreter source code very much so I wouldn't be able to point you to anything particularly useful.

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