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From: dmitry@elros.cbb-automation.de (Dmitry Kazakov)
Newsgroups: comp.lang.ada
Subject: Re: Thoughts on the ADaOS user program interface
Date: Fri, 07 Sep 2001 08:24:48 GMT
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Date: 2001-09-07T08:24:48+00:00
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On 6 Sep 2001 14:18:04 -0400, ka@sorry.no.email (Kenneth Almquist)
wrote:

>(Note: In addition to the use suggested here, pragma Separate_Tag
>would improve the performance of types like Ada.Strings.Unbounded,
>where a tagged type is required but the tag is rarely used.  When this
>pragma is applied to a type, it is not possible to redispatch in the
>primitive subprograms for that type, because that would require using
>the tag in a context where there is no class-wide pointer to the
>object.)

Not only that. If tag is separate, one could make *all* types tagged.
Class-wide values would consist of tag + specific value. Pointers to
class-wides would be tag + pointer to a specific value.

This way one could make Boolean, Integer etc tagged and most of type
attributes ['Value, 'Image ...] dispatching.

Sorry for off-topic, but I could not resist (:-))

Regards,
Dmitry Kazakov