Re: Can .ads be compiled alone?

[Robert A Duff <bobduff@shell01.TheWorld.com>]

Jeffrey Carter <spam.jrcarter.not@spam.not.acm.org> writes:

> This is an idiosyncrasy of GNAT's source-based compilation model.

Yes, that's the way GNAT works, but I don't think it's directly
related to the source-based model.  AdaMagic uses a source-based model,
but you have to compile package specs.  I don't know of any compilers
that use a non-source-based model and behave like GNAT w.r.t. package
specs, but I don't see why it couldn't be done.

>... When you
> compile something that withs a package, GNAT also looks at the source file for
> the pkg spec. So GNAT normally only compiles a pkg body; typically the message
> when one tries to compile a spec that has a body is something like "cannot
> produce object code for a package specification" (I haven't tried it recently).
> You can check a pkg spec that has a body with -gnatc,

Yes, and you can also do that withOUT -gnatc.  ;-)

>...and compile a spec that
> doesn't have a body, or compile a spec along with its body by compiling the body.
>
> Other compilers have other ways of dealing with this, and require that a pkg
> spec be compiled before you can compile something that withs it.

Yup.  The Ada RM doesn't define how compilers are invoked and so on --
that's up to the individual Ada implementation.

- Bob