monkey-patching python一个实例方法


monkey-patching python an instance method

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我正在尝试修补一个类实例，但不太明白如何修补一个类方法没问题。

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>>> class Simple(object):
...     def make(self, arg):
...         return arg * 2
...
>>> s = Simple()
>>> def times_four(self, arg):
...   return arg * 4
...
>>> Simple.make = times_four
>>> s.make(10)
40

但是假设我只想替换make，那么最简单的方法是什么？

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>>> def times_eight(self, arg):
...   return arg * 8
>>> s.make = ???
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你可以创建新的实例times_eightby using its method"__get__特殊法：P＞＜／

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>>> class Simple(object):
...     def make(self, arg):
...         return arg * 2
...
>>> s = Simple()
>>> def times_eight(self, arg):
...     return arg * 8
...
>>> s.make = times_eight.__get__(s, Simple)
>>> s.make(10)
80
>>> type(s.make)
<type 'instancemethod'>
>>>
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哦！P＞＜／

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>>> import types
>>> s.make = types.MethodType(times_eight, s, Simple)
>>> s.make(10)
80

方法selfonly get the automatically when passed Arg(not received from the class from the实例dict)，我知道你need to通安1 -精氨酸功能有：P＞＜／

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s.make = lambda arg: times_eight(s, arg)

(你可以简化functools.partialthat with)。P＞＜／

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