Re: Interfacing to C: big structures

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

Adam Beneschan <adam@irvine.com> writes:

> I thought of something like this, but Maciej said something about
> wanting to avoid dynamic memory,...

I think Maciej is trying to avoid heap allocation, because then you have
to worry about deallocation.  But dynamic-sized allocation on the stack
should be OK in that regard.  If you don't like the dynamic size (it
does introduce some inefficiency), then you could do this:

S_Size : constant := 24; -- or whatever you know it is
pragma Assert (S_Size = Size_Of_S);
type S is new Ada.Streams.Stream_Element_Array (1 .. S_Size);
for S'Alignment use ...;

Now the Ada compiler knows the right size statically.
If the C code changes, you have to change 24 to something else,
but at least you get notified to do so (the simplest testing
will fail on the Assert).

- Bob