Z23EEEB4347BDD255DDFC6B7EE9AB 中的返回 function 和返回 function object 有什么区别？

Question

def speak():
    def whisper():
        print('ased')
    return whisper()

speak()

While using decorators what we do is return function object, but here we have returned the function (return whisper()), so can someone explain what is the difference between returning a function and returning a function object?

Answer 1

The return function object, returns the function and in Python can be assigned to another function which also becomes callable function. The new assigned function can be called to perform the same task.

Where as in return function, it returns the value and only the same function will be called to perform the function. It can not be assigned.

Answer 2

when you return the function, it will execute the print('ased') when create a new variable. But if you return the object, you can execute the variable that will perform the same task

Answer 3

You are writing a function that has a nested function inside it. The normal intent of this is that you would have some other code in there more interesting than what you are doing, but I realize this is just a toy for you to try the idea, so we can ignore that.

The real problem you have is the return. You code:

def speak():
    def whisper():
        print('ased')
    return whisper()

speak()

has the return statement actually calling the whisper() function and then returning the result of that function call, which is nothing since whisper() does not return anythin it just prints.

So it is basically the same as if you had written:

def speak():
    return print('ased')

speak()

or just:

def speak():
    print('ased')

speak()

What you probably intended was to leave off the () 's like this return whisper so that it did not call the function, but actually returned a reference to the function that would be returned and could later be called, like this:

def speak():
    def whisper():
        print('ased')
    return whisper

func = speak()
...
func()

Which would not print anything when speak was called but would return a function reference that you can save and then call later (in this case func ).

The above is not the way a decorator works, but it does use the same principal of defining an internal function and then returning a reference to that function.