在函数结束（例如，检查失败）之前，在python中退出函数（没有返回值）的最佳方法是什么？

Let’s assume an iteration in which we call a function without a return value. The way I think my program should behave is explained in this pseudocode:

for element in some_list:
    foo(element)

def foo(element):
    do something
    if check is true:
        do more (because check was succesful)
    else:
        return None
    do much much more...

If I implement this in python, it bothers me, that the function returns a None. Is there a better way for “exiting a function, that has no return value, if a check fails in the body of the function”?

You could simply use

return

which does exactly the same as

return None

Your function will also return None if execution reaches the end of the function body without hitting a return statement. Returning nothing is the same as returning None in Python.

I would suggest:

def foo(element):
    do something
    if not check: return
    do more (because check was succesful)
    do much much more...

you can use the return statement without any parameter to exit a function

def foo(element):
    do something
    if check is true:
        do more (because check was succesful)
    else:
        return
    do much much more...

or raise an exception if you want to be informed of the problem

def foo(element):
    do something
    if check is true:
        do more (because check was succesful)
    else:
        raise Exception("cause of the problem")
    do much much more...