Michael Urman wrote:
> I'm trying to find some real world examples of a pygame event loop
>
>that really show the benefit of supporting named constants and
>expressions. I may mess up irrelevant details, but the primary case
>looks something like the following (perhaps Pete Shinners could point
>us to a good example loop online somewhere):
>
> for event in pygame.event.get():
> if event.type == pygame.KEYDOWN: ...
> elif event.type == pygame.KEYUP: ...
> elif event.type == pygame.QUIT: ...
>
>Here all the event types are integers, but are clearly meaningless as
>integers instead of an enumeration. I'd be sorely disappointed with
>the addition of a switch statement that couldn't support this as
>something like the following:
>
> for event in pygame.event.get():
> switch event.type:
> case pygame.KEYDOWN: ...
> case pygame.KEYUP: ...
> case pygame.QUIT: ...
>
>
With the simplified proposal, this would be coded with an inverse mapping:
for event in pygame.event.get():
switch eventmap[event.type]:
case 'KEYDOWN': ...
case 'KEYUP': ...
case 'QUIT': ...
Hopefully, the static() proposal will work-out and the mapping won't be
necessary. If it does work-out, you'll also get more error-checking
than you get with either the if-elif version or the simplified switch-case.
>
>I also would like to see a way to use 'is' instead of (or inaddition
>to) '==' for the comparison, but I don't have any use cases behind
>this.
>
>
If speed is the goal, this isn't necessary. The internal equality check
takes a shortcut in the event of an identity match.
OTOH, if the goal is having several distinct cases that are equal but
not identical, then that's another story. I suggest leave the initial
switch syntax as simple as possible and just switch on id(object).
Raymond
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