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From: "Chad R. Meiners" <crmeiners@hotmail.com>
Newsgroups: comp.lang.ada
Subject: Re: Ideas for Ada 200X "left hand side" repeater.
Date: Tue, 17 Jun 2003 17:03:53 -0400
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"Bill Findlay" <yaldnifw@blueyonder.co.uk> wrote in message
news:BB14D345.35C8%yaldnifw@blueyonder.co.uk...
>>
> > What about using 'is' to express identity? e.g.:
> >
> >  Pixel is Screen.Buffer(i) in Pixel := Pixel + 1;

I think I like this.

> > It's not exactly concise, though. Nor is any 'implicit renaming'
solution.

Perhaps simplified is a better description because it allows the written
format to enhance readability.

Pixel is Screen.Buffer(i) in
    Pixel := Pixel + 1;

It also separates the dual concerns of naming complex expression and having
clear statements while keeping the names in sight of each other. Perhaps the
above sample is too simple how about

Pixel is Screen.Buffer(i) in
    Pixel := To_Red(Get_Green(Pixel)) + To_Green(Get_Blue(Pixel)) +
To_Blue(Get_Red(Pixel));

versus

declare
    Pixel : Buffer_Element renames Screen.Buffer(i);
    Red   : constant Scale := Get_Red(Pixel);
    Green : constant Scale := Get_Green(Pixel);
    Blue  : constant Scale := Get_Blue(Pixel);
begin
    Pixel := To_Red(Green) +  To_Green(Blue) + To_Blue(Red);
end;

or

Screen.Buffer(i) := To_Red(Get_Green(Screen.Buffer(i))) +
                               To_Green(Get_Blue(Screen.Buffer(i))) +
                               To_Blue(Get_Red(Screen.Buffer(i)));

> However, it does generalize, to, e.g.:
>
>    V is A_Variable in Perform_Operations_On(V);

This too I like.