Re: Implementing an Ada compiler and libraries.

[Lucretia <lucretia9@lycos.co.uk>]

On May 11, 8:14 am, Gautier <gaut...@fakeaddress.nil> wrote:
> > What if the body of one or two require the subprogram three? Is this a
> > form of forward declaration? Would interleaving specs and body's cause
> > problems? Probably.
>
> Most Ada compilers allow multiple compilation units in the same file.
> They are just treated the same way as if they were each in its file.
> It would be surprising if this was not described somewhere in the Manual...

There isn't as far as I've found. It's implementation dependent.

> In your example, three is not visible by the body of one or two.
>
>    package one is procedure z; end;
>    package two is procedure z; end;
>    procedure three is begin null; end;
>    package body one is procedure z is begin null; end; end;
>    package body two is procedure z is begin three; end; end;
>
> ObjectAda says to that:
> multipack: Error: line 5 col 44 LRM:4.1(3), Direct name, three, is not
> visible, Ignoring future references

Yeah, my example wasn't complete, just an example ordering I slapped
together.

> conversely...
>
>    package one is procedure z; end;
>    package two is procedure z; end;
>    procedure three is begin null; end;
>    package body one is procedure z is begin null; end; end;
>    with three;
>    package body two is procedure z is begin three; end; end;
>
> compiles fine.

Now, I take it there would be a compiler error if three came after
two?

> And yes you can put others specs after bodies, just a spec of a package after
> its body seems not ok:
>
>    package body one is procedure z is begin null; end; end;
>    package one is procedure z; end;
>
> multipack: Error: line 1 col 15 LRM:7.2(4), corresponding package spec not
> found, continuing

Ok.

So, it seems that Aonix just enforces that the dependencies within a
file be sorted out by the programmer, and that the specs are always
before the bodies. What if you do:

package one is ... end one;
package two is ... end two;
package body one is ... end one;
package body two is ... end two;

I take it, this is allowed?

Thanks,
Luke.