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From: mheaney@on2.com (Matthew Heaney)
Newsgroups: comp.lang.ada
Subject: Re: Ada 200X
Date: 13 Jun 2003 07:00:39 -0700
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Date: 2003-06-13T14:00:39+00:00
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Craig Carey <research@ijs.co.nz> wrote in message news:<jvf4evgqd71kuqeoc2c2c81mdcck01g8qa@4ax.com>...
> 
> Some sample techniques for speeding up some Ada 95 programs:

At least in Charles, you can optimize string and vector container
manipulation by calling Resize, which preallocates the internal
buffer.  This is useful if you know the ultimate size of the
collection apriori:

procedure Op (S : in out String_Container_Subtype) is
begin
   Resize (S, Size => 80); //for example

   Append (S, "first");
   Append (S, "second");
   ...
end Op;

Both the string and vector containers have a To_Access function, which
returns a pointer to the internal buffer.  This allows you to
eliminate copying.  For example, instead of this:

procedure Op (S : in String_Container_Subtype) is
begin
   Put_Line (To_String (S)); -- not as efficient as below
end;

do this instead, if you're really concerned about efficiency:

procedure Op (S : in String_Container_Subtype) is
   Line : String renames To_Access (S) (1 .. Length (S));
begin
   Put_Line (Line);
end;

The string container package guarantees that To_Access always returns
a non-null access object.

The combination of Resize and To_Access should improve efficiency.