Comments on book review

dgary at ecsvax.UUCP dgary at ecsvax.UUCP
Wed May 2 02:24:24 AEST 1984

   The referenced article refers to the textbook approach to programming, i.e.
design, program, debug.  The book in question even suggests that failing to
plan the program out carefully before writing is dangerous and bug-prone.  The
author of the article asks if anyone actually programs that way, and what people
think of that approach.
   Well, I for one subscribe to the notion of "stepwise refinement" or
(more poetically) "creeping elegance."  The idea is to write a program that
(1) is small (2) does at least some of what you want the final program to
do, or shoots in that direction (3) works and (4) is easy to modify.
   This makes it possible to program almost bug-free, and to catch bugs almost
as soon as they occur (so you don't have to go on a bug-hunt later on).  The
idea is to keep adding to the program until you get what you want (or maybe
something better).  A big plus to this approach is that the program remains
modifiable - one of the reasons for the high cost of software maintenance
(I suspect) is the tacit assumption that the program will never have to be
changed.  If you know for a fact from the word go that mods are coming, you'll
write a better program most of the time.  And certainly one that is easier to
fix and improve.
   So no, I don't believe in plan-code-test.  I believe in plan a little, code
a little, test a little, plan a little, code a little, test a little....
   Long live Yourdon!

   Best,  D Gary Grady, Duke University
   {decvax or whatever}!mcnc!ecsvax!dgary

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