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From: Keith Thompson <kst@cts.com>
Subject: Re: Representation question (void *)
Date: 1999/11/16
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Date: 1999-11-16T00:00:00+00:00
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"Lipscomb, Kevin" <KLipscomb@C2CEN.USCG.mil> writes:
> How would one represent the following C declaration in Ada 95?
> 
>    void *data;
> 
> Is this just a placeholder for a pointer that should never be referenced?

The following is from an article I posted a few months ago.

My suggestion:

    type Void_Pointer is private;
    Null_Void_Pointer : constant Void_Pointer;
    ...
    type Void_Pointer is new Interfaces.C.Strings.chars_ptr;
    Null_Void_Pointer : constant Void_Pointer
        := Interfaces.C.Strings.Null_Ptr;

By making it a private type, you avoid making the operations in
Interfaces.C.Strings visible to clients.

The closest semantic equivalent to C's void* is Ada's System.Address.
This is *almost* certain to be compatible (I doubt that there's an
existing system on which they're different), but the language doesn't
guarantee it.

-- 
Keith Thompson (The_Other_Keith) kst@cts.com  <http://www.ghoti.net/~kst>
San Diego Supercomputer Center           <*>  <http://www.sdsc.edu/~kst>
"Oh my gosh!  You are SO ahead of your time!" -- anon.