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From: Brian May <bam@snoopy.apana.org.au>
Newsgroups: comp.lang.ada
Subject: Re: APQ
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Date: Wed, 05 Jan 2005 08:32:53 +1100
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Date: 2005-01-05T08:32:53+11:00
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>>>>> "Dmitry" == Dmitry A Kazakov <mailbox@dmitry-kazakov.de> writes:

    Dmitry> You probably mean this:

    Dmitry> function Copy (C : Root_Connection_Type'Class)
    Dmitry> return Root_Connection_Ptr is
    Dmitry> begin
    Dmitry> return new Root_Connection_Type'Class'(C);
    Dmitry> end Copy;

    Dmitry> This indeed cannot work for limited types. This was the
    Dmitry> reason why Copy was declared abstract primitive instead:

    Dmitry> function Copy (C : Root_Connection_Type)
    Dmitry> return Root_Connection_Ptr is abstract;

    Dmitry> It will dispatch to an implementation which knows how to
    Dmitry> copy itself:

I am under the impression (perhaps wrong impression, I haven't tested
it) that

A := Copy(C);

will not work if C is a limited type, as there is an implied copy
operation from the RHS to the LHS.

Also the thread "Return_By_Reference or Return_By_Copy (GNAT bug?)" might
be relevant here.
-- 
Brian May <bam@snoopy.apana.org.au>