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From: Robert A Duff <bobduff@world.std.com>
Subject: Re: Problem trying to implement generics.
Sender: bobduff@world.std.com (Robert A Duff)
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Date: Fri, 13 Apr 2001 23:01:02 GMT
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Date: 2001-04-13T23:01:02+00:00
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"Ayende Rahien" <Dont@spam.me> writes:

> BTW, is there any reason why I can't use out parameter with a function?

Because it's not allowed.  ;-)

Hmm, are we going have this argument again?  Oh well, it's kind of fun,
in a time-wasting sort of way.  Here goes:

If I ran the circus, functions would be allowed to have 'out' and 'in
out' parameters.

- Bob

P.S. One workaround is to use access parameters.

Another workaround is to declare a limited type, with a component that
always points to itself:

    type T is tagged limited
        record
            Self_Reference: T_Ptr := T'Unchecked_Access;
            ...
        end record;

If you pass this thing as an 'in' parameter to a function, the function
can modify it by following the Self_Reference pointer.  This works
because no constant objects of type T can exist.  It seems a lot like
"cheating", doesn't it?