如何覆盖在python中的导入类中的类调用？ [英] How can I override class call inside of an imported class in python?

问题描述

假设我在 modul1 中有以下脚本：

Let say I have the following script in modul1:

class IN(object):
    def __init__(self):
        pass

class C(object):
    def __init__(self, x):
        pass

    def func(self):
        cl = IN()

$ b b

然后我要在另一个脚本中使用 C 类：

from modul1 import C 

class IN(object):
    def __init__(self):
        pass

class C2(C):
    def __init__(self, x):
        C.__init__(self, x)

我可以通过在 C2 类中创建同名的方法来覆盖 C 类的func方法。

I can override C class's func method by creating a method with the same name in C2 class.

但是如何重写 modul1 的I​​N类里面的任何调用 C 类 IN 类中的调用 modul2 ？

我想改变原始 IN 类的一些功能。我要 C 类调用

But how can I override any call of modul1's IN class inside of imported C class with IN class in the caller modul2?
I want to change some functionality of original IN class. I want C class to call in the row

cl = IN()

我自己的 IN修改的功能。

my own IN() class with the altered functionality.

推荐答案

module1.py：

module1.py:

class IN(object):
    def __init__(self):
        print "i am the original IN"

class C(object):
    def __init__(self, x):
        pass

    def func(self):
        print "going to create IN from C's func"
        cl = IN()

module2.py：

module2.py:

import module1

class IN(object):
    def __init__(self):
        print "I am the new IN"

class C2(module1.C):
    def __init__(self, x):
        super(C2, self).__init__(x)


print "\n===Before monkey patching==="
C2(1).func()
#monkey patching old In with new In
module1.IN = IN
print "\n===After monkey patching==="
C2(1).func()

在运行脚本module2.py时输出：

Output while running the script module2.py:

===Before monkey patching===
going to create IN from C's func
i am the original IN

===After monkey patching===
going to create IN from C's func
I am the new IN

你可以看到如何调用module2的In构造函数。

You can see how the module2's In constructor is being called.

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