如何从函数中的exec返回值? [英] How to return value from exec in function?

问题描述

我尝试:

def test(w,sli):
    s = "'{0}'{1}".format(w,sli)
    exec(s)
    return s

print test("TEST12344","[:2]")

其返回"TEST12344" [:2]

its return 'TEST12344'[:2]

如何从函数中的exec返回值

How to return value from exec in function

推荐答案

exec()不仅评估表达式，还执行代码.您必须在exec()调用中保存参考.

exec() doesn't just evaluate expressions, it executes code. You would have to save a reference within the exec() call.

def test(w, sli):
    exec('s = "{}"{}'.format(w, sli))
    return s

如果只想计算一个表达式，请使用eval()，并保存对返回值的引用:

If you just want to evaluate an expression, use eval(), and save a reference to the returned value:

def test(w,sli):
    s = "'{0}'{1}".format(w,sli)
    s = eval(s)
    return s

但是，我建议尽可能避免在任何实际代码中使用exec()和eval().如果使用它，请确保有充分的理由这样做.

However, I would recommend avoiding exec() and eval() in any real code whenever possible. If you use it, make sure you have a very good reason to do so.

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