Re: [pygame] the game.Mainloop() myth

[kschnee@xxxxxxxxxx]

On Thu, October 25, 2007 4:41 pm, RR4CLB wrote:
> Take a look at this:
> Python Library Reference
...
> __main__
> -- Top-level script environment
> This module represents the (otherwise anonymous) scope in which the
> interpreter's main program executes -- commands read either from standard
> input, from a script file, or from an interactive prompt. It is this
> environment in which the idiomatic ``conditional script'' stanza causes a
> script to run: if __name__ == "__main__": main() Previous Page

Ah, OK, I think I see the confusion's source.

When Python runs, the file that you're actually running is recognized by
the interpreter as having a special designation, "__main__". __This
syntax__ is also used unofficially for lines like:
__version__ = "12.7.41"

Having the line:
if __name__ == "__main__":

...At the bottom of your code creates a conditional auto-run section,
something that runs whenever the Python file is loaded, but only if it's
being run as the main program as opposed to being imported by another
file.

For instance, I've got a module called Coral that makes a tiled graphics
engine but doesn't include game logic. To test Coral I've got some code at
the bottom of that module's code inside that "if" line, set up to run a
demo/test. So when I open up Coral.py and run it, the demo runs, but when
I say "import Coral" in something else, the demo doesn't run.

The line "if __name__ == "__main__": main()" is a slightly different way
of doing what I did, just putting the "demo" code inside a function
instead of sitting at the bottom of the file. There isn't actually a
built-in function called "main". For Pygame purposes, you can and should
make your own main loop, and don't need to trap your code inside somebody
else's loop logic.