On Mon, Oct 22, 2012 at 7:45 AM, Matthew Ngaha <chigga...@gmail.com> wrote:
> In many of the tutorial examples ive come across, the main code's program is
> never at the top level, but always in a function of some sort. i understand
> why but, there is always a different way used to access the main code, i
> want to know which is the best.
>
>
> main()
> main's code
>
> #top level
> main()
>
> they call the main program by simply calling the main function. I've also
> seen a more complcated:
>
> if __name__ == '__main__':
> main()
>
Every module in python has a name. You have probably seen code like this:
import os
import sys
os and sys are modules and their names are 'os' and 'sys'
When you write your own program in a file 'my_code.py' and then run it
by typing:
python my_code.py
The name of your program is '__main__'
So when you write:
if __name__ == '__main__':
<your code here>
The code will only run when you run the file directly. Many times,
the functions in your file could be used in other programs. In that
case you might have a file called my_new_code.py
In my_new_code.py you could import the other file so you could use its
functions. Like this:
import my_code
When you import the file, it is not the __main__ code. Its name will
be my_code. And so the code you have in the part I marked <your code
here> will never run. It only runs when you run the file directly.
--
Joel Goldstick
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