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Correction to definition of controlled/uncontrolled assertion clauses.

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Author:halw
Date:2011-07-30T23:19:50.000000Z


git-svn-id: https://svn.eiffel.com/eiffel-org/trunk@948 abb3cda0-5349-4a8f-a601-0c33ac3a8c38
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halw
2011-07-30 23:19:50 +00:00
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documentation/current/solutions/concurrent-computing/concurrent-eiffel-scoop/index.wiki
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@@ -232,7 +232,7 @@ The role of the precondition is somewhat different in SCOOP than in sequential E
In concurrent Eiffel, the same correctness conditions are still valid, but there are cases in which we must view the clients role here a little differently. In the case of a precondition clause that depends upon an [[Concurrent Eiffel with SCOOP#Controlled expressions|uncontrolled]] object, even if the client tests the condition ahead of the call, there is no assurance that action by some other concurrent processor may have invalidated the precondition clause between the time that the check was made and the time that the feature application takes place. So, the client cannot be held responsible establishing that this clause holds. This type of precondition clause is called an '''uncontrolled precondition clause'''.
{{definition|Controlled/uncontrolled assertion''' (precondition or postcondition) '''clause| A precondition or postcondition clause for a feature <code>f</code> is controlled if, after substitution of actual arguments for formal arguments, <code>f</code> involves only calls on entities which are controlled in the context of the routine which is the caller of <code>f</code>. <br/><br/>Otherwise it is an '''uncontrolled assertion''' (precondition or postcondition) '''clause'''. }}
{{definition|Controlled/uncontrolled assertion''' (precondition or postcondition) '''clause| A precondition or postcondition clause for a feature <code>f</code> is controlled if, after substitution of actual arguments for formal arguments, the clause involves only calls on entities which are controlled in the context of the routine which is the caller of <code>f</code>. <br/><br/>Otherwise it is an '''uncontrolled assertion''' (precondition or postcondition) '''clause'''. }}
So, the determination of whether a particular precondition or postcondition clause is controlled or uncontrolled depends upon the context of the calling routine. That means that a particular clause on feature <code>f</code> might be considered controlled when <code>f</code> is called by one caller, but uncontrolled when called by a different caller.