Re: OpenGL in Ada

[Shark8 <onewingedshark@gmail.com>]

On Jul 11, 2:46 pm, a...@att.net wrote:
> In <i1bktn$uc...@speranza.aioe.org>, tmo...@acm.org writes:
> >> >>>  Procedure Color    ( red, green, blue : in double );
> >> >>>  Procedure Color    ( red, green, blue : in float );
>
> >> One problem you'll have is if a user wants to make a call with all
> >> literals, i.e. Color(1, 2, 3) or Color(1.0, 2.0, 3.0), the compiler
> >> won't know which version to use.  The best solution I've found (besides
> >> making users specify a type)
>
> >And what's wrong with requiring the user to be unambiguous by specifying
> >a type?  It's unlikely there will be a lot of calls with all literals
> >(unless generated by some program) so it shouldn't be onerous.  And
> >"Float'(1.0)" is clearer to the person reading the code five years
> >from now than "Color_F".
>
> What your are forgetting is the openGL is a specification from the openGL
> group ( opengl.org ), it is just like the Ada RM in that respect.  For a
> program or package, to be classified as openGL it must comply with "openGL
> group" openGL specification.  Changing any API part nullify the use of
> openGL in any part of your system.
>
> So, adding or altering any definitions about the given API must comply with
> the openGL specification. Names of the API functions and procedures with
> the API defined types are set by this openGL group.

That seems, on its face, to contradict BrianG's claim:

> What you have is a way to do it, but that's not what the OP posted.  He had
> all procedures named Color, so the user doesn't need to worry about
> implementation.  (If I use Color for Double and want to change my program to
> use Float, I have to change the names of all calls, even if I use calls where
> the compiler could determine what I want - and not just calls to Color, many
> routines would have the same issue.)  This is also what the OpenGL
> documentation implies should be done in a language like Ada.

But, if he's correct in this earlier post:
> (I've tried starting a similar effort, but never got very far.  I was using
> the OpenGL "red book" as a basis; I find it interesting that the OpenGL
> definition recognizes that "some languages like Ada and C++" could implement
> names this way, but every Ada library I've seen follows the C naming scheme.)

Then my renaming (to get rid of the gl- prefix and parameter-type-
postfix) and
overloading them all is a valid OpenGL API.

>
> visitwww.opengl.org
> for more information on openGL and the "openGL group"
>
> Also, you may find the API specifications predefined with examples in C that
> you can alter to Ada there as well.