Re: Array Help?

["Randy Brukardt" <randy@rrsoftware.com>]

"Robert A Duff" <bobduff@shell01.TheWorld.com> wrote in message 
news:wcclinkxvth.fsf@shell01.TheWorld.com...
> Ludovic Brenta <ludovic@ludovic-brenta.org> writes:
>
>> Robert A Duff writes on comp.lang.ada:
>>>      Foo (Slide(A (3 .. 8)));
>>
>> Doesn't that involve copy-in and copy-out between the slice and a
>> temporary object of type Slide?  Grossly inefficient, methinks.
>
> No, I don't see any need for the compiler to make a copy here.
> It just needs to pass the 1..6 bounds, plus a pointer to
> the array elements.
>
> I'm too lazy to check the machine code to see whether GNAT
> makes a copy, but I don't see why it would.  Nor any other
> Ada compiler.

Surely Janus/Ada does not. It just makes a new array descriptor and passes 
that -- exactly the same as it would do for the original slice. The only 
interesting question is whether Janus/Ada would be smart enough to get rid 
of the (unused) original slice's array descriptor. I didn't check, but I'm 
sure there wouldn't be one in this case (static bounds). I have no idea what 
would happen if the bounds were dynamic (as in my better example).

                               Randy.