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From: rfarris@serene.UUCP (Rick Farris)
Newsgroups: comp.software-eng,comp.lang.ada
Subject: comments on comments on reusability
Keywords: comments
Message-ID: <419@serene.UUCP>
Date: 23 Feb 89 20:41:47 GMT
References: <1813@goofy.megatest.UUCP> <20233@agate.BERKELEY.EDU> <9689@ihlpb.ATT.COM> <6093@medusa.cs.purdue.edu>
Reply-To: rfarris@serene.UUCP (Rick Farris)
Organization: Serenity BBS, Del Mar, California
List-Id: <comp.lang.ada>

In article <6093@medusa.cs.purdue.edu> rjh@cs.purdue.EDU (Bob Hathaway) writes:

> (I write)
> >|This seems to go backwards.  Programmers should first design
> >|their software then implement it.  You seem to be advocating 
> >|implementation then design.  The descriptive algorithm should 
> >|come first, then the code.

> In article <9689@ihlpb.ATT.COM>, nevin1@ihlpb.ATT.COM (Liber) writes:
> >I have a problem with Top-Down programming (design then
> >implementation); it happens to be the same problem I have with
> >Bottom-Up programming (implementation then design).  You so eloquently
> >point it out in your next sentence:  

Something that neither one of you guys addressed, and that I think is
crucial to the whole "Top-Down Design" issue, is reusability.
Top-down design implies leaves that are custom made for the program
at hand.  Reusability implies molding the problem definition around
leaf (and maybe not-so-leaf) modules that are already available.
After all, for a hardware design, you wouldn't design your own ICs,
would you?

One of Ada's major strengths is it's facilities to design for re-use,
and we designers have to come to grips with the idea that we're not
going to be doing "optimal" designs anymore.

> |Just follow the convention that when code is updated so are the
> |comments.

Hmm.  That's ok when you're working on small projects.  I've never
seen it work in real-life when many programmers were involved.


Rick Farris   RF Engineering  POB M  Del Mar, CA  92014   voice (619) 259-6793
rfarris@serene.cts.com     ...!uunet!serene!rfarris       serene.UUCP 259-7757