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From: Frank Piron <nospam@konad.net>
Newsgroups: comp.lang.ada
Subject: Re: Variant vs. Tagged Type
Date: Thu, 06 Nov 2003 08:22:03 +0100
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Am Wed, 05 Nov 2003 17:40:45 GMT hat Jeffrey Carter <spam@spam.com> 
geschrieben:

> Frank Piron wrote:
>
>> is it possible to make some general statements
>> concerning the alternative variant vs. tagged
>> type with respect to runtime performance?
>> For example:
>> if we have an array A 1) of type access to a variant
>> 2) of type access <TYPE>'Class
>> what can be said about the runtime performance
>> of the expression
>> A(I).<component>?
>
> It sounds as if you're engaging in premature optimization (the root of 
> all evil). Do it whichever way is best suited to the problem, and see if 
> the result is fast enough. 99.99% of the time, the microsecond 
> differences you're worrying about don't make a difference.
>
Currently i'm working on an ORACLE access library on top of
oci. Yesterday i've done some benchmark tests. I experienced
differences in runtime performance up to a factor of 4 while
fetching and extracting 10_000 rows in using a variant instead
of an array of class wide pointers for the db_row_type. The
compiler is gnat 3.15p on windows.
Fortunately ada gives alternatives ;-)
Frank