Re: [AD] Platform specific functions in A5 [was Re: Windows Addition for Message Parsing]

[Evert Glebbeek <eglebbk@xxxxxxxxxx>]

On 8 Oct 2008, at 20:30, Chris Robinson wrote:
> > Ok, the function won't work on other systems, but, does other OS
> > require you to "catch" "messages" to add functionality? I'm pretty
> > sure there are more libraries for unix/OSX that can coexist with
> > allegro and may add things that in windows could be only done by
> > parsing messages.
>
> So even more platform specific code? "For Windows, use this Allegro
> functionality. For other OSs we have to use an external lib." Isn't  
> the point
> of Allegro to provide cross-platform capabilities, without the user  
> having to
> directly use platform-specific libs?

Yes, so as I said, for this particular case, we should not add this  
function so people can use more functionality (multiple mice) - if we  
want that we should implement support for that properly.
The API is not fixed in stone at the moment, though I don't think we  
want to be doing any radical design changes.
Also, if we decide that we do want this, it's not something that we  
need to implement *now*, just something that can be implemented later  
without breaking (or disfiguring) the API too much. If it fits on  
smoothly, it can be in, say, 5.0.1 rather than 5.0.0

> It's better to have a cross-platform function that no-ops on other  
> platforms,
> than a platform-specific function that's not available on other  
> systems, IMO.

I think I agree with this - although it would be a bit silly if we  
know it's only ever going to work on one system (the again, did  
scrolling displays really work on anything other than DOS? I don't  
mean the hack job that was in the X11 port).
Having more platform specific functions makes it harder to write  
portable code, but having platform specific functions that maskerade  
as platform neutral functions is arguably worse because they suggest  
functionality that isn't there.

> Does it have to be, though? If it can be exposed in a platform- 
> neutral way,
> and be useful on multiple platforms, IMO, we should try to make it  
> platform
> neutral.

Apparently, intercepting messages cannot really be abstracted into a  
platform neutral function, unfortunately. I figured it'd be very hard  
to do, but thought we should discuss it anyway.

> FWIW, multiple mice is supported by X11, AFAIK, so it's not  
> platform specific
> and shouldn't require platform-specific code to use. If someone  
> needs to
> manually parse platform-specific window messages to do it in  
> Windows, it's
> definitely a candidate to make an API for it in a cross-platform way.

I agree.

Evert