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From: Duncan Sands <baldrick@free.fr>
Newsgroups: comp.lang.ada
Subject: Ada.Containers.Vectors - querying multiple elements
Date: Tue, 26 Apr 2005 13:43:52 +0200
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Date: 2005-04-26T13:43:52+02:00

I've been playing around with Ada.Containers.Vectors (part of Ada 2005,
see http://charles.tigris.org/; look for AI-302) and noticed that
there's no way to view or operate on a "slice" of a vector.  There's a
routine

   procedure Query_Element
       (Container : in Vector;
        Index     : in Index_Type;
        Process   : not null access procedure (Element : in Element_Type));

for looking at one element; I'd like something like this:

   procedure Query_Elements
       (Container   : in Vector;
        First_Index : in Index_Type;
        Last_Index  : in Extended_Index;
        Process   : not null access procedure (Elements : in Element_Array));

where Element_Array would be:

   type Element_Array is array (Index_Type range <>) of Element_Type;

Is there any reason no such routine exists?  It would be good to have for both
efficiency reasons and simple implementation of certain classes of algorithms.
In my case I have a "divide and conquer" recursive algorithm which while it
can be written using the current package, would be simpler to write if something
like Query_Elements existed.

All the best,

Duncan.