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From: Wes Groleau <groleau+news@freeshell.org>
Newsgroups: comp.lang.ada,comp.lang.c++,comp.realtime,comp.software-eng
Subject: Re: Teaching new tricks to an old dog (C++ -->Ada)
Date: Wed, 09 Mar 2005 22:26:16 -0500
Organization: Ain't no organization here!
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Xref: g2news1.google.com comp.lang.ada:8997 comp.lang.c++:44893
 comp.realtime:1173 comp.software-eng:4735
Date: 2005-03-09T22:26:16-05:00
List-Id: <comp.lang.ada>

Hans Malherbe wrote:
> * case statements (Ada's equivalent of a switch in C++) are required
>   to handle all possible cases.  Thus it is impossible to forget one.
>   And, of course, there is no "break;" crap in Ada.
> 
> Prevents fall through.

And it prevents forgetting to put in the break--an error
so common that the feature was explicitly prohibited in
the Ada specs.

> This is more in the C++ tradition. The programmer has choice.
> In C++ you can extend the type system to achieve this and more
> (someone mentioned dimensional analysis), just not with typedef.

In C++ and Java, you can do a heck of a lot to program
type safety and abstraction.  Problem is that it _is_
a heck of a lot -- for example, to emulate what Ada does
with things like

    type Possible_Speed is                range 0.0 .. 140.0;
    constant Speed_Limit is 55.0;
    subtype Legal_Speed is Possible_Speed range 0.0 ..  Speed_Limit;
    type Direction is mod 360;

    V : Legal_Speed;
    C, D : Direction;

Before you say it doesn't take much, remember your solution
should allow

    V := Speed_Limit - 15.0;

raise an exception on
    .....
    V := 55.1;

and it should refuse to compile the typo

    V := D;

Another problem is that because of the work involved in
enforcing abstractions with classes, most Java programmers
(probably C++, too) would rather just say

    double V;
    double C, D;

-- 
Wes Groleau

A pessimist says the glass is half empty.

An optimist says the glass is half full.

An engineer says somebody made the glass
        twice as big as it needed to be.