在不传递参数的情况下在函数中使用变量 [英] Use a Variable in a Function Without Passing as an Argument

问题描述

在python中，有什么方法可以让函数使用变量并返回它而不将其作为参数传递?

In python is there any way at all to get a function to use a variable and return it without passing it in as an argument?

推荐答案

您提出的要求是可能的.如果某个函数没有重新绑定(例如，分配给它)一个名称，而是使用了该名称，则该名称将被视为一个 global ，例如:

What you ask is possible. If a function doesn't re-bind (e.g, assign to) a name, but uses it, that name is taken as a global one, e.g:

def f():
    print(foo)

foo = 23
f()

将按照您的要求进行操作.但是，这已经是一个可疑的想法:为什么不只是def f(foo):并调用f(23)，那么更直接，更清晰?！

will do what you ask. However, it's a dubious idea already: why not just def f(foo): and call f(23), so much more direct and clearer?!

如果函数需要绑定名称，那么即使global语句允许使用该名称，它也会变得更加可疑...:

If the function needs to bind the name, it's even more dubious, even though the global statement allows it...:

def f():
    global foo
    print(foo)
    foo += 1

foo = 23
f()
print(foo)

在这里，好得多的替代方案是:

Here, the much better alternative would be:

def f(foo):
    print(foo)
    foo += 1
    return foo

foo = f(23)
print(foo)

效果相同-更清洁，可维护性更好的结构.

Same effect - much cleaner, better-maintainable, preferable structure.

为什么，当一种更好的方法更容易，更清洁时，您正在寻找劣等(虽然可行)的方法??！

Why are you looking for the inferior (though feasible) approach, when a better one is easier and cleaner...?!

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