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From: Franck Arnaud <Franck_Arnaud@stratus.com>
Subject: Re: Precondition Checking For Ada 0X (Was: Separation of IF and Imp:
 process issue?)
Date: 1997/09/17
Message-ID: <341FB47D.1B81@stratus.com>#1/1
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References: <mheaney-ya023680001009971956580001@news.ni.net>
 <EGLBMK.A5I@syd.csa.com.au> <341eac5e.0@news.uni-ulm.de>
 <184347314wnr@eiffel.demon.co.uk> <EGME6n.470@world.std.com>
Organization: (not speaking for any)
Newsgroups: comp.lang.ada,comp.lang.eiffel
Date: 1997-09-17T00:00:00+00:00
List-Id: <comp.lang.ada>



Robert A Duff:

> My understanding is that the compiler generates run-time checks for
> invariants at both entry to and exit from each feature.

Correct.

>  If so, why?  How can the check-upon-entry ever fail, since the
> invariant must be true initially, and must be true after every exit?

If the invariant is other.some_condition, other's state may have changed
since last time.