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From: "Dmitriy Anisimkov" <anisimkov@yahoo.com>
Newsgroups: comp.lang.ada
Subject: Re: GCC 4.0 Ada.Containers Cursor danger.
Date: 7 Jul 2005 05:29:43 -0700
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Date: 2005-07-07T05:29:43-07:00
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<<
> Maybe i do not good understand the meaning of "versatility", but I was
> able fast to do whatever i want whithout cursors under ADT.

You keep saying, "Mine was fast!" and you don't tell us how
fast compared to what. How can repeated hashing be as fast as
direct access via a cursor?>>

I do not think that "repeated hashing be as fast as
direct access via a cursor".

If I need direct access to elements, I put dynamically allocated object
(maybe smart pointer) into container, and keep access where i need.
I think it is more honestly than to keep cursors.
So I take responsibility for deallocation. And library does not have to
check
for invalid cursors.

<<How can a linear search be as fast as
direct access via a cursor?>>

Strange question. I do not know answer. I did not propose linear
search.

<<There is a performance cost if a library forces its user to
repeatedly look up a key by recomputing slots each time, for example.>>

If user need direct access, he has to create this access himself.

<<So you say we need a safe container and we need the first
formulation of the loop, not the second, which is likely faster.>>

In the safe containers loop should be inside generic procedure, and
without
cursors.

generic
   procedure Process (Key : Key_Type; Value : Value_Type; Stop : out
Boolean);
procedure Generic_Iteration (Container : Container_Type);
--  Process all elements untill Stop.

<<procedure Silly is>>

The container is not thread safe I see, so, the nobody would modify it
untill
we are working on it. It would be better to put elements into container
after
the loop. If we really need to put it there before loop, I would put
access
into containers and modify content via access.