[hibernate-issues] [Hibernate-JIRA] Commented: (HV-421) Reconsider behavior of parameter validation for inheritance hierarchies

[Hardy Ferentschik (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HV-421?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=39890#action_39890 ] 

Hardy Ferentschik commented on HV-421:
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The most important thing is that this only applies for method parameters. Thinking about the spec I would say there is room for interpretation and adjustments (in a later version). The return value constraints are a conjunction of all constraints which is needed to be consistent with the whole getter validation. 
Your approach with throwing exceptions seems reasonable even on the first glance seems limiting. It is imo more consistent with the spec than using disjunction. We can always revisit the behavior later. We can add a respective comment to the documentation.

> Reconsider behavior of parameter validation for inheritance hierarchies
> -----------------------------------------------------------------------
>
>                 Key: HV-421
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HV-421
>             Project: Hibernate Validator
>          Issue Type: Bug
>          Components: engine
>            Reporter: Gunnar Morling
>            Assignee: Gunnar Morling
>             Fix For: 4.2.0.Beta2
>
>
> Let A extend B and A#foo() override B#foo(). When validating an invocation of A#foo() the current implementation will evaluate all parameter constraints defined at A#foo() *and* B#foo(). That way foo()'s preconditions defined in B are strengthened by A. 
> According to the ["Programming by contract"|http://en.wikipedia.org/wiki/Programming_by_contract] article on WP this is not allowed, subtypes may only weaken preconditions defined by supertypes. The common implementation pattern for this is to combine the preconditions within a hierarchy by a logical OR, meaning the weakest precondition in the hierarchy applies.
> Note that postconditions (return value constraints) may be strengthened (but not weakened) by subtypes. Therefore the current implementation (AND combination) should be correct here.

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