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Date: Wed, 06 Jul 2005 10:02:24 +0200
From: Georg Bauhaus <bauhaus@futureapps.de>
Organization: future apps GmbH
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Newsgroups: comp.lang.ada
Subject: Re: GCC 4.0 Ada.Containers Cursor danger.
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Dmitriy Anisimkov wrote:
> I think that safety is a good feature even for the regular
> applications. It would help to reduce debugging time
> 
> Matthew told:
> <<Safety is also in tension with flexibility and efficiency. >>
> 
> I think that containers without cursors could loose some flexibility,
> but do not loose functionality and performance.

If you remove cursors, like for example from Insert/4,
then you will definitly have algorithms that will run
more slowly using more memory cells or register cells.

This is because cursors on dynamic containers work to achieve
some efficiency. It's worthwhile to read up on the AI 302.

I'm assuming you somehow found a way around the case where you have
to compare strings and/or hash them in order to repeatedly
find a key? Or how do you remember a position in a dynamic
container? Using a cursor, certainly O(1) is less than
O(hashing + string comparisons)?

And how do you _not_ loose efficiency if on every loop
iteration you check the validity of your variables related
to container elements?

> And definately gaining
> in safety and in the debugging time.

You are gaining exceptions in some cases.

If there were a number of generic algorithms working on
top of Ada.Containers, would they be useful in your work?

How about idiomatic uses of the library?


Georg