From: sal714@rs710.gsfc.nasa.gov (Stephen A. Leake)
Subject: Re: Types with physical dimension
Date: 03 Oct 1994 17:31:09 GMT
Date: 1994-10-03T17:31:09+00:00 [thread overview]
Message-ID: <SAL714.94Oct3133110@rs710.gsfc.nasa.gov> (raw)
In-Reply-To: graham@clsi.COM's message of 27 Sep 1994 22:18:41 GMT
In article <GRAHAM.94Sep27181841@canopus.clsi.COM> graham@clsi.COM
(Paul Graham) writes:
...
One can model physical types in Ada by using private types, but
this involves writing a lot of operators. What do Ada programmers
do to guard against dimensional errors?
I run robots with Ada, so I deal with real dimensions all the time. Very early
on, I started to write a package that enforced dimensionality; I defined
METERS, METERS_PER_SECOND, etc. I quickly discovered that even simple equations
need up to cubic dimensions, in all combinations of length, mass and time.
Defining all these types and the associated operators was far too
time-consuming to be worth it. So now I rely on code reviews and careful
testing.
The moral; strong typing is nice, but is no substitute for careful design
and thorough testing.
--
Stephen Leake, NASA Goddard Space Flight Center
email: Stephen.Leake@gsfc.nasa.gov
next prev parent reply other threads:[~1994-10-03 17:31 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
1994-09-27 22:18 Types with physical dimension Paul Graham
1994-09-28 13:59 ` Robert Dewar
1994-09-30 2:06 ` R_Tim_Coslet
1994-10-03 17:31 ` Stephen A. Leake [this message]
1994-10-04 11:51 ` Robert I. Eachus
1994-10-04 19:45 ` Mark A Biggar
[not found] ` <CxBBx8.7L@irvine.com>
1994-10-13 22:15 ` gamache
1994-10-12 3:43 ` Matt Kennel
1994-10-04 14:56 ` Robert Dewar
1994-10-05 14:53 ` Bob Gilbert
1994-10-05 8:38 ` Jean-Pierre Rosen
1994-10-05 10:35 ` Stephen J Bevan
1994-10-05 13:17 ` Jean-Pierre Rosen
1994-10-05 15:48 ` Norman H. Cohen
-- strict thread matches above, loose matches on Subject: below --
1994-09-28 10:55 Simtel20 Transfer
1994-09-28 18:56 ` Mark A Biggar
1994-10-04 2:06 ` lmiller
1994-09-28 19:28 Paul Pukite
[not found] <GRAHAM.94Sep27181841@canopus.clsi.com>
1994-09-28 17:36 ` William Brennan
1994-09-28 21:41 ` Tucker Taft
1994-09-29 4:11 ` Robert Dewar
1994-09-29 11:19 ` Peter Hermann
1994-09-30 10:17 ` Dr John Stockton
1994-10-03 4:37 ` Robert Dewar
1994-09-29 13:37 ` Tucker Taft
1994-10-03 4:40 ` Robert Dewar
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