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From: donh@syd.csa.com.au (Don Harrison)
Subject: Re: Safety-critical development in Ada and Eiffel
Date: 1997/07/23
Message-ID: <EDrHBA.H0u@syd.csa.com.au>#1/1
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Newsgroups: comp.object,comp.software-eng,comp.lang.ada,comp.lang.eiffel
Date: 1997-07-23T00:00:00+00:00
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Ken Garlington wrote:

:Richie Bielak wrote:

:> I always thought it would be nice to have postconditions of the form:
:> 
:>         ensure
:>                 execution_time < 10 -- 10 milliseconds, let's say
           end
           ^^^
           my addition
:> 
:> So an exception would be raised if the routine took too long
:> to execute.
:
:Of course, you have to decide if "execution time" includes the time for
:the postcondition (including any code that executes after the actual
:test instruction)!

It would be the duration when the expression "execution_time" is evaluated.
There would be no statements following the assertion so it should be accurate 
enough for most purposes. If not, you can apply a small compensating adjustment 
to the relational expression:

         ensure
                 execution_time < 9.99  -- milliseconds
         end


:We usually have such measurements _outside_ the code sequence being
:measured (i.e., in the scheduler).

..in which case, you'd presumably be subject to the timing inaccuracies of 
the scheduler, anyway.


Don.
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Don Harrison             donh@syd.csa.com.au