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From: mike@zin.world.com
Subject: A note on Ada subtyping
Date: 1999/02/22
Message-ID: <7asf3h$9gm@drn.newsguy.com>#1/1
X-Deja-AN: 447228092
Organization: Newsguy News Service [http://www.newsguy.com]
Newsgroups: comp.lang.ada
Date: 1999-02-22T00:00:00+00:00
List-Id: <comp.lang.ada>


As I am learning Ada (I use the GNAT compiler, an
excellent compiler btw), I am more impressed with it.

This is one simple example, where Ada helped me find a bug
in my logic that I would not been able to find as easily
if I was using C or C++ or even Java.

I needed a variable, that logically could not take in values
over some range, say n..m, becuase this is the nature of
the problem was. So I defined this variable to be
of of this type. (where in C/C++/Java, I would simply have
made it an 'int' or a 'short' as almost eveyone else would have),
giving the variable a much larger range that is really needed.

During running of the program, the Ada run-time generated a 
contraint error exception as soon the program tried to
assign a value to this variable outside this range.

This quickly lead me to see where my logic error was, and I fixed
it.

This is an excelllent language. By using variables with restricted
ranges and values, as in this case, Ada helped me find a prblem in
my logic!

Ada is giving me the power to write a more tight code thanks
to the ability to easily define types as required by the 
problem domain.

I know in the other languages, I would have missed this 
logic error, or at least it would have taken longer to find it.

Makes me wonder, why isn't the whole world programming in Ada?

Mike.