11:52 a.m.
On Mon, Jan 21, 2013 at 11:35 AM, Emmanuel Bernard
<emmanuel(a)hibernate.org>wrote:
On the subject, Gunnar and I were discussing three valid options to
define a constraint as cross-parameter constraint:
## @CrossParametersConstraint
(first off I hate the name, can't we find a better one?)
@Constraint(validatedBy=ObjectScriptAssert.class)
@CrossParametersConstraint(validatedBy=ObjectScriptAssert.class)
public @interface ScriptAssert { ... }
## @Constraint for both
@Constraint(validatedBy=ObjectScriptAssert.class
validatedByForCrossParameters=ObjectScriptAssert.class)
public @interface ScriptAssert { ... }
## @Validates on ConstraintValidator
@Constraint(validatedBy=ObjectScriptAssert.class)
public @interface ScriptAssert { ... }
@Validates({CROSS_PARAMETERS, ANNOTATED_ELEMENTS})
public class ObjectScriptAssert implements
ConstraintValidator<ScriptAssert,Object[]> { ... }
## Thoughts
I think I like @CrossParametersConstraints more than @Constraint for
both as it makes things explicit and keep the simple use case as is.
But I am intrigued by the @Validates option. In many ways, it's similar
to how we resolve the right constraint validator based on the type. The
only difference is that the @Validates annotation refines how Object[]
should be interpreted. It "fits better" in my opinion.
My concern around the latest option is that it forces us to be a
subclass of ConstraintViolation for the foreseeable future including
when we reopen the type-safe options we explored in
http://beanvalidation.org/proposals/BVAL-232/
Thoughts and comments?
So you're saying @Validates would eliminate the need for a separate
CrossParameterConstraintValidator interface? FWIW, it seems to me that the
separate interface just feels more straightforward.
Matt
Emmanuel
On Tue 2013-01-15 15:14, Gunnar Morling wrote:
> 2013/1/15 Emmanuel Bernard <emmanuel(a)hibernate.org>
>
> > I can live with that but we must make it crystal clear that in case of
> > ambiguity, we raise an exception. Otherwise, someone changing the
method
> > sig might have some nasty surprises.
> >
>
> And which of the options
>
>
@CrossParameterConstraint(validatedBy=MyCrossParameterValidator.class)
> @Constraint(validatedBy=MyGenericValidator.class)
> public @interface MyConstraint { ... }
>
> vs.
>
> @Constraint(
> validatedBy=MyGenericValidator.class,
> crossParameterValidatorType=MyCrossParameterValidator.class
> )
> public @interface MyConstraint { ... }
>
> would you prefer?
>
> Personally I'd lean towards the latter, since there would be exactly one
> meta-annotation denoting an annotation as constraint annotation type,
with
> all attributes for the required configuration.
>
> If following the 2nd approach, we should IMO add a default clause to
> validatedBy() (set to the empty array), allowing for
> the convenient definition of cross-parameter only constraints. According
to
> [1] this change would be binary-compatible.
>
> But this is no strong preference, I could also live with the two separate
> annotations.
>
> --Gunnar
>
> [1]
>
http://wiki.eclipse.org/Evolving_Java-based_APIs_2#Evolving_API_interface...
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