如何更改 Python 函数的表示? [英] How do I change the representation of a Python function?

问题描述

<预><代码>>>>def hehe():...返回垃圾邮件"...>>>代表(呵呵)'<函数 hehe 在 0x7fe5624e29b0>'

我想要:

<预><代码>>>>代表(呵呵)'hehe 函数由很棒的程序员创建'

我该怎么做?将 __repr__ 放在 hehe 函数中不起作用.

如果你们想知道我为什么要这样做:

<预><代码>>>>默认字典(呵呵)defaultdict(, {})

我只是不喜欢它在这里显示的方式.

解决方案

通常，当您想更改函数的某些内容时，例如函数签名、函数行为或函数属性，您应该考虑使用装饰器.因此，您可以通过以下方式实现您想要的:

class change_repr(object):def __init__(self, functor):self.functor = 函子# 让我们从原始函数中复制一些关键属性self.__name__ = functor.__name__self.__doc__ = functor.__doc__def __call__(self, *args, **kwargs):返回 self.functor(*args, **kwargs)def __repr__(self):return '<由 ...创建的函数 %s>'% self.functor.__name__@change_repr定义 f():返回垃圾邮件"打印 f() # 垃圾邮件print repr(f) # <function hehe created by ...>

请注意，您只能使用基于类的装饰器，因为您需要覆盖 __repr__ 方法，而使用函数对象则无法做到这一点.

>>> def hehe():
...     return "spam"
... 
>>> repr(hehe)
'<function hehe at 0x7fe5624e29b0>'

I want to have:

>>> repr(hehe)
'hehe function created by awesome programmer'

How do I do that? Putting __repr__ inside hehe function does not work.

EDIT:

In case you guys are wondering why I want to do this:

>>> defaultdict(hehe)
defaultdict(<function hehe at 0x7f0e0e252280>, {})

I just don't like the way it shows here.

解决方案

Usually, when you want to change something about the function, say function signature, function behavior or function attributes, you should consider using a decorator. So here is how you might implement what you want:

class change_repr(object):
    def __init__(self, functor):
        self.functor = functor

        #  lets copy some key attributes from the original function
        self.__name__ = functor.__name__
        self.__doc__ = functor.__doc__

    def __call__(self, *args, **kwargs):
        return self.functor(*args, **kwargs)

    def __repr__(self):
        return '<function %s created by ...>' % self.functor.__name__


@change_repr
def f():
    return 'spam'


print f()  # spam
print repr(f)  # <function hehe created by ...>

Note, that you can only use class based decorator, since you need to override __repr__ method, which you can't do with a function object.

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