函数内静态变量的 Python 等价物是什么? [英] What is the Python equivalent of static variables inside a function?

问题描述

这个 C/C++ 代码的惯用 Python 等价物是什么?

What is the idiomatic Python equivalent of this C/C++ code?

void foo()
{
    static int counter = 0;
    counter++;
    printf("counter is %d\n", counter);
}

具体来说，相对于类级别，如何在函数级别实现静态成员?将函数放入一个类中会改变什么吗?

specifically, how does one implement the static member at the function level, as opposed to the class level? And does placing the function into a class change anything?

推荐答案

有点颠倒，但这应该有效:

A bit reversed, but this should work:

def foo():
    foo.counter += 1
    print "Counter is %d" % foo.counter
foo.counter = 0

如果你想要计数器初始化代码在顶部而不是底部，你可以创建一个装饰器:

If you want the counter initialization code at the top instead of the bottom, you can create a decorator:

def static_vars(**kwargs):
    def decorate(func):
        for k in kwargs:
            setattr(func, k, kwargs[k])
        return func
    return decorate

然后使用这样的代码:

@static_vars(counter=0)
def foo():
    foo.counter += 1
    print "Counter is %d" % foo.counter

不幸的是，它仍然需要您使用 foo. 前缀.

It'll still require you to use the foo. prefix, unfortunately.

^{(来源:@ony)}

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