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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Time to join the fold?
Date: 1999/02/01
Message-ID: <EACHUS.99Feb1154518@spectre.mitre.org>#1/1
X-Deja-AN: 439481005
References: <78abg4$cnc$1@its.hooked.net>
 <F5zFII.GrI.0.-s@inmet.camb.inmet.com> <78i8s4$hth$1@its.hooked.net>
 <swhalenF67p8v.HGq@netcom.com>
Organization: The Mitre Corp., Bedford, MA.
Newsgroups: comp.lang.ada
Date: 1999-02-01T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <swhalenF67p8v.HGq@netcom.com> Steve Whalen <swhalen@netcom.com> writes:

 > Spend more time thinking about your application's data, and your
 > application "as data" (by "application as data" I mean revisit program
 > logic, and see if it can be better represented in a "soft" data
 > structure somewhere)...
 > Even more importantly I want to benefit from thinking more deeply
 > about WHY some data should be a represented one way, instead of
 > another...
 > Bottom line: Getting the data structures and representations right
 > lets Ada help you build higher quality applications...

   Amen!  I find that effort devoted to the package specifications,
which contain most of the data types, either exported or in the private
part, is the key part of programming in Ada.  Once you know which
types should be used where and why, writing the code is easy.

   But there is another part to Ada think.  In many languages you are
looking for a model which best fits the solution.  In Ada it is almost
always a big win to fit the model to the problem space.  Generics and
generic instantiation can be used to map a solution onto your problem.

   To take one simple example, if you are going to sort a list the
ordering relation is a generic argument that can be a quite complex
function of the data.  If the sort order changes, you change that
function, not the data.  But if your requirements change in such a way
that you need to represent additional aspects of reality in the data,
this requires additional modifications.

   Hmmm... Not quite simple expressed that way.  Say you have a
bibliography.  The effort required to sort by author, title, Library
of Congress number, or even author's middle name, is small, assuming
that all are present in the data.  Your problem space is a
bibliography, the sort package's problem space is lists to be sorted,
and all you have to do is provide the glue.



--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...