Is it common to write a lot of code under if name == 'main': statement

Question

my current coding style is like

import xxx

def fun1()
def fun2()
...

if __name__ == '__main__': 

    task = sys.argv[1]
    if task =='task1':
        do task1
    elif task == 'task2':
        do task2
    ...

my problem is that the part of the code under

if __name__ == '__main__':

is quite huge comparing to the functions defined above and I was told this is not a good programming style. It is due to the fact that I modify stuff and do experiment in each tasks frequently and I want to separate those part of the code away from functions which are less likely to be modified. I want to learn more advice here, thanks!

It's better to wrap it all up into a single `main()` function, then call this function under your `if __name__ == '__main__'` — AdrienW, Aug 04 '16 at 09:41
I agree with BusyAnt, define a main() and do it there because if `__name__ == __main__` only gets called if this is the main routine, so on import it won't ... — AnyOneElse, Aug 04 '16 at 09:43

Pax Vobiscum · Accepted Answer · 2016-08-04T09:46:08.607

4

Like BusyAnt said, the common way to do it is

import xxx

def fun1()
def fun2()
...



def main():
    task = sys.argv[1]
    if task =='task1':
        do task1
    elif task == 'task2':
        do task2
    ...

if __name__ == '__main__':
    main()

The upside of this is it does not run on import, but main() can still be run from another module or file if so preferred.

edited Aug 04 '16 at 09:46

answered Aug 04 '16 at 09:42

Pax Vobiscum

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1

Thanks for quoting @Uzzee, I was actually writing an answer from it myself. :) – AdrienW Aug 04 '16 at 09:46
2

Say this file is named `script1.py` and if we import it to another file called `script2.py`, the ``__name__`` variable will not equal to `'__main__'` but to `'script1'`, and therefore `main()` will not be run by default. We can however choose to run it by typing `script1.main()` in our script2.py file. – Pax Vobiscum Aug 04 '16 at 09:53

score 3 · Answer 2 · edited Sep 27 '17 at 04:46

It is not forbidden to write a lot of things under if __name__ == '__main__', though it is considered better and more readable to wrap everything up in a main() function. This way, the code in main() isn't executed when you import this module in another module, but you can still choose to run it, by calling imported_script.main().

Your code would then look like this :

import xxx

def fun1()
def fun2()
...


def main():
    task = sys.argv[1]
    if task =='task1':
        do task1
    elif task == 'task2':
        do task2
    ...

if __name__ == '__main__':
    main()

I encourage you to read about what does this if statement do, among the many questions asked about it.

Is it common to write a lot of code under if __name__ == '__main__': statement

2 Answers2

Is it common to write a lot of code under if name == 'main': statement