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From: rav@goanna.cs.rmit.EDU.AU (++           robin)
Subject: Re: next "big" language?? (disagree)
Date: 1996/06/12
Message-ID: <4plaa6$c7a@goanna.cs.rmit.EDU.AU>#1/1
X-Deja-AN: 159711491
references: <4p1l65$35qi@info4.rus.uni-stuttgart.de>
 <4p60nk$imd@euas20.eua.ericsson.se> <4p8lmq$oq7@goanna.cs.rmit.edu.au>
 <4pj8p7$h9r@goanna.cs.rmit.EDU.AU> <ag129.511.000A9CE9@ucs.cam.ac.uk>
organization: Comp Sci, RMIT, Melbourne, Australia
newsgroups: 
 comp.lang.pascal,comp.lang.c,comp.lang.misc,comp.lang.pl1,comp.lang.ada
nntp-posting-user: rav
Date: 1996-06-12T00:00:00+00:00
List-Id: <comp.lang.ada>


	ag129@ucs.cam.ac.uk (A. Grant) writes:

	>In article <4pj8p7$h9r@goanna.cs.rmit.EDU.AU> rav@goanna.cs.rmit.EDU.AU (++           robin) writes:
	>>        >euahjn@eua.ericsson.se (Henrik Johansson) writes:
	>>        >>assertion expression found in other languages like Eiffel (
	>preconditions,>        >>postconditions, assertions).

	>>---What is the point of this?
	>>   A declaration buried somewhere else, and a test.
	>>   Why not something in clear english, which doesn't need a
	>>reference to some other part of the program, like:

	>>   if mod(x, 2) ^= 0 then
	>>        put ('The value of x is not odd.');

	>The point of assertions is not to print messages for the 
	>programmer.

---If you don't tell the programmer that something is wrong,
there's really little point in putting
extraneous clutter in the program.

	> You can use them to allow the compiler to 
	>optimise safely, provide a contractual interface between 
	>modules, and for preconditions, postconditions, loop invariants
	>etc. when proving the correctness of programs.

	>E.g. the assertion that X is odd could form part of the 
	>declared interface to a module whose implementation was hidden.  

---That may be so, but if the program doesn't feed the
fact that there is a violation, then there's no point in the
program.