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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Expressive Case Statements (was: Software landmines)
Date: 1998/09/02
Message-ID: <EACHUS.98Sep2141351@spectre.mitre.org>#1/1
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References: <slrn6sopmg.4fg.jdege@jdege.visi.com>
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Organization: The Mitre Corp., Bedford, MA.
Newsgroups: comp.lang.ada
Date: 1998-09-02T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <35ECDA3F.3372@atlas.otago.ac.nz> "Dr Richard A. O'Keefe" <ok@atlas.otago.ac.nz> writes:

  > Concerning decision tables, the EVALUATE statement in COBOL,
  > and Robert I. Eachus's suggestion for doing them in Ada,
  > I don't know what the COBOL standard says about EVALUATE,
  > but there was one point about decision tables which seems
  > to have been missed:

  >   - as well as the condition *combinations* being complex,
  >   - the condition *elements* may be complex, and
  >   - you don't want to evaluate them if you don't have to...

  True, but from experience decision tables are not for situations
where evaluating all the decision variables is potentially harmful.
There are often cases where you nest decision tables because some
predicates should only be evaluated in some cases.  Too many don't
cares should also be taken as an indication that you have merged
tables that should be separate.
--

					Robert I. Eachus

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