Re: Conditional compilation in Ada?

["Alex R. Mosteo" <devnull@mailinator.com>]

Nick Roberts wrote:
> "Marius Amado Alves" <amado.alves@netcabo.pt> wrote in message 
> news:mailman.103.1100630792.10401.comp.lang.ada@ada-france.org...
> 
>>>Any hints?
>>
>>Gnatprep.
> 
> 
> In a little more detail, declare the things that differ (types, associated 
> operations) in two separate packages, say Stuff_For_Playstation and 
> Stuff_For_XBox, then put something like this:
> 
> Compile_Target := XBox
> 
> into a text file called "targspec.txt" (say), and then something like this 
> in the appropriate places in your source files:
> 
>    with Stuff_For_$Compile_Target;
>    ...
>    package Target_Specific renames Stuff_For_$Compile_Target;
>    ...
>       Target_Specific.Reset_Joystick; -- or whatever
> 
> and rename every so doctored source file myfile.ads to myfile.adsp (and 
> myfile.adb to myfile.adbp) and then run:
> 
>    gnatprep myfile.adsp myfile.ads targspec.txt -c -r
> 
> for each such source file, and then compile as normal. Documentation for 
> gnatprep is in the GNAT User's Guide.
> 
> Obviously, you change "Compile_Target := XBox" to "Compile_Target := 
> Playstation" to recompile for a different target.
> 
> The idea is to minimise the number of times you use a $ macro or #if in your 
> source files, within reason, and put as much as possible into the different 
> specific packages. Things tend to be easier to debug this way. You may find 
> that you do not have to use gnatprep at all, but instead you could just have 
> a separate file "target_specific.ads" which contains the two lines:
> 
>    with Stuff_For_XBox;
>    package Target_Specific renames Stuff_For_XBox;
> 
> which you simply change to:
> 
> 
>    with Stuff_For_Playstation;
>    package Target_Specific renames Stuff_For_Playstation;
> 
> in order to recompile for a different target.

What I do is to have a folder for every platform-specific code. It must 
conform to a predefined spec, as suggested. Then I have two rules in a 
Makefile. One issues the gnatmake -Iplatform1 and the other -Iplatform2.