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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: OO, C++, and something much better!
Date: 1997/01/28
Message-ID: <EACHUS.97Jan28144125@spectre.mitre.org>#1/1
X-Deja-AN: 212797723
references: <JSA.97Jan16141937@alexandria> <5buodl$bci@boursy.news.erols.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: 
 comp.object,comp.lang.c++,comp.lang.ada,comp.lang.smalltalk,comp.lang.eiffel
Date: 1997-01-28T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <32ED2448.685A@parcplace.com> Eric Clayberg <clayberg@parcplace.com> writes:

  > OK, then, back it up. So far, *you* haven't *proven* anything. The above
  > is yet another unsubstantiated claim that statically typed systems are
  > somehow more reliable than dynamically typed systems. Show me some proof
  > that Smalltalk is somehow less reliable for building applications than
  > any arbitrary statically typed language.

   Try this.  Build a new aircraft with radical new avionics
requirements, or a vertical takeoff and landing rocket (DC-X), or a
railroad traffic control system for high-speed trains, or run an
air-traffic control system, or anything where the software is large
and complex and it has to work the first time.  Write the operational
software in Smalltalk.  Come back when your software has been proven
in service.

   Langauges other than Ada have been used for this, including Jovial,
Fortran, C and even CMS-2.  But to my knowledge neither C++ or
Smalltalk has been used.  NOT because they are bad languages, but
because in this role it is difficult to do the amount of "bench"
checking required to get someone to foot the bill and take the risk of
actually fielding the software.  Well, not quite true, AT&T has used
C++ in phone switching systems and gotten roundly castigated for it
when the inevitable failures occured.

   By the way, you can write Ada code which uses dynamic dispatching,
and there are some safety-critical systems where it is permitted.  The
same with pointers, dynamic allocations, and tasking.  This is not
about such features, this is about how much confidence can you have
before the software is run.  When it absolutely has to work the first
time, you get very conservative in your design rules.

--

					Robert I. Eachus

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