Re: Exclude parts of a package

[Shark8 <onewingedshark@gmail.com>]

On Friday, December 6, 2013 1:48:43 PM UTC-7, Felix Krause wrote:
> 
> This is an interesting approach, but in my case, that would lead to 
> massive code duplication because I don't really have child packages to 
> choose from (same goes for having multiple spec files). I rather need 
> to add or exclude subroutines of one package. Moving it to a child 
> package will not work because it needs to be a primitive operation of a 
> tagged type defined in the original package.

Easy enough solution:
1) Define everything [all of OpenGL, or at least portion-X (X : Types, Functions, etc)] in one big package; for the current version (4.3, IIRC).*
2) Define version-packages which repeat the spec of the appropriate functions and use renames in their body.
3) Use the rename technique given by Brian.

Ex:
--------------------------------------------------

Package Main_Stuff is
  Procedure Bob;  -- Introduced in v.1.
  Procedure Tim;  -- Introduced in v.1.2.
  Procedure Dave; -- Introduced in v.1.3.
  Procedure Bill; -- Introduced in v.1.3.

private
  -- Stubs, to avoid having to provide a body.
  Procedure Bob  is null;
  Procedure Tim  is null;
  Procedure Dave is null;
  Procedure Bill is null;
end Main_Stuff.

-- Def v.1.
private with Main_Stuff;
Package Stuff_1_1 is
  Procedure Bob;
private
  Procedure Bob renames Main_stuff.Bob;
end Stuff_1_1;


-- Def v.1.2.
private with Main_Stuff;
Package Stuff_1_2 is
  Procedure Bob;
  Procedure Tim;
private
  Procedure Bob renames Main_stuff.Bob;
  Procedure Tim renames Main_Stuff.Tim;
end Stuff_1_2;

---- Brian's renaming trick:
with Stuff_1_2;
package Stuff renames Stuff_1_2;

---- Client code:
with Stuff;
procedure Do_Stuff is --....

-------------------------------------------------------------------
* In my OpenGL binding TAO-GL my plan was/is similar to this except
  the bingings query opengl for parameters and build the types from
  the results (ie NUMBER_OF_LIGHTS) via generic instantiation, then
  that would instantiate the functions (ensuring the functions) are
  not called w/ inappropriate parameters.

* TAO-GL: https://github.com/OneWingedShark/TAO-GL
  NOTE:   GitHub version at the state *before* I decided
          to make the Functions package generic.