Python：同名的常规方法和静态方法 [英] Python: Regular method and static method with same name

问题描述

我有一个Python类，其中包含许多方法。我想要这些方法之一有一个静态对应，即，一个静态方法具有相同的名称 - 可以处理更多的参数。经过一些搜索，我发现我可以使用 @staticmethod 装饰器来创建一个静态方法。

I have a Python class, which contains a number of methods. I want one of those methods to have a static counterpart—that is, a static method with the same name—which can handle more arguments. After some searching, I have found that I can use the @staticmethod decorator to create a static method.

为了方便起见，我创建了一个简化的测试用例，可以重现问题：

For convenience, I have created a reduced test case which reproduces the issue:

class myclass:

    @staticmethod
    def foo():
        return 'static method'

    def foo(self):
        return 'public method'

obj = myclass()
print(obj.foo())
print(myclass.foo())

我希望上面的代码打印以下内容：

I expect that the code above will print the following:

public method
static method

打印以下内容：

public method
Traceback (most recent call last):
  File "sandbox.py", line 14, in <module>
    print(myclass.foo())
TypeError: foo() missing 1 required positional argument: 'self'

从这里，我只能假设调用 myclass.foo（）试图调用它的非静态对应没有参数因为非静态方法总是接受参数 self ）。这个行为阻碍了我，因为我期望任何调用静态方法来实际调用静态方法。

From this, I can only assume that calling myclass.foo() tries to call its non-static counterpart with no arguments (which won't work because non-static methods always accept the argument self). This behavior baffles me, because I expect any call to the static method to actually call the static method.

我测试了这个问题Python 2.7 和 3.3，只接收相同的错误。

I've tested the issue in both Python 2.7 and 3.3, only to receive the same error.

为什么会发生这种情况，我该怎么做来修复我的代码，使其打印：

Why does this happen, and what can I do to fix my code so it prints:

public method
static method

如我所料？

推荐答案

类似的问题在这里：在python编程中使用相同名称的重写方法

函数是通过名称查找的，所以你只需使用实例方法重新定义foo。在Python中没有诸如重载函数这样的东西。你可以用一个单独的名字写一个新的函数，或者你提供的参数可以处理两者的逻辑。

functions are looked up by name, so you are just redefining foo with an instance method. There is no such thing as an overloaded function in Python. You either write a new function with a separate name, or you provide the arguments in such a way that it can handle the logic for both.

换句话说，你可以没有静态版本和同名的实例版本。如果你看看它的 vars ，你会看到一个 foo 。

In other words, you can't have a static version and an instance version of the same name. If you look at its vars you'll see one foo.

In [1]: class Test:
   ...:     @staticmethod
   ...:     def foo():
   ...:         print 'static'
   ...:     def foo(self):
   ...:         print 'instance'
   ...:         

In [2]: t = Test()

In [3]: t.foo()
instance

In [6]: vars(Test)
Out[6]: {'__doc__': None, '__module__': '__main__', 'foo': <function __main__.foo>}

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