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From: David Botton <David@Botton.com>
Subject: Re: win32ada design question/problem
Date: 1998/11/19
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Date: 1998-11-19T00:00:00+00:00
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Mats Weber wrote:

> On the other hand,
>
>    type String_Access is access String;
>
>    function C_Function (X : in String_Access);
>
>    C_Function(S'Unchecked_Access);
>
> will sometimes not work because some compilers (and that includes GNAT)
> use fat pointers for access to unconstrained arrays (I am not saying
> that this is bad).
>
> so you have to do this instead:
>
>    C_Function(S(S'first)'Unchecked_Access);
>
> which does not make clear that S is passed as a whole.
>
> The second problem is that people see a compiler message like "object
> has accessibility level deeper than access type" and instead of using
> 'Unchecked_Access, they move the declaration to the library level and
> create non task safe code. I am not making this up, see the samples
> directory that comes with the win32ada binding.

Why wouldn't you use:

function C_Function ( X : C.char_array ) returns C.Int;
-- int c_function ( char* x);

pragma Import (C, C_Function);

>From my understanding it will be passed by_referrence, ie. as a char *


For other record types

type Z is record
    a : C.Int;
end record;

pragma Convention(C, Z);

procedure C_Procedure ( Y : Z );
-- void* c_procedure ( z* y );

pragma Import  (C, C_Procedure);

David Botton