[jira] Commented: (BEEHIVE-179) context.getControlPropertySet() should return null for non-existent annotation

["Kyle Marvin (JIRA)" <be...@incubator.apache.org>]

     [ http://issues.apache.org/jira/browse/BEEHIVE-179?page=comments#action_57782 ]
     
Kyle Marvin commented on BEEHIVE-179:
-------------------------------------

This is wrapped up in the following commented out code, from the impl of org.apache.beehive.controls.runtime.bean.ControlBeanContext.getControlPropertySet():

        // TODO: Add a PropertySet meta-attribute that indicates the PropertySet is optional.
        // This implies:  a) no getters/setters, and b) the PropertySet can appear to be
        // 'null' from the impl perspective if unset; otherwise, a PropertySet containing all
        // default values will be returned.
        //if (!map.containsPropertySet(propertySet))
        //    return null;


If a PropertySet/annotation is optional, then we can't really generate the client-visible getter for it.   There is no way to express an unset value, unless it is the default.  If the impl isn't using defaulted semantics, it seems wrong to  tell the client that the default is the property value.   I feel pretty strongly that client/impl views of property state must be identical.

Similarly, if 'unset' is a valid value for the property, there would need to be a way to 'unset' a property, which again doesn't make sense using the standard JavaBeans accessor model.

So the proposed resolution would be to add an 'optional' boolean attribute to the PropertySet annotation type, which has the semantics described in the comment above.


> context.getControlPropertySet() should return null for non-existent annotation
> ------------------------------------------------------------------------------
>
>          Key: BEEHIVE-179
>          URL: http://issues.apache.org/jira/browse/BEEHIVE-179
>      Project: Beehive
>         Type: Bug
>   Components: Controls
>     Versions: V1Beta
>  Environment: Windows
>     Reporter: Lawrence Jones
>     Priority: Critical

>
> I call
> ServiceControl.TypesJarName typesJarNameAnn =
>                 (ServiceControl.TypesJarName)context.
>                     getControlPropertySet(ServiceControl.TypesJarName.class);
> in the Impl of my control (ServiceControl). TypesJarName is a valid annotation which is defined in the public interface  but not used in either the public interface nor in the JCX.
> I expected to receive null but instead I get a non-null object with defaulted values for its members.
> This is at odds with the javadoc for the API ControlBeanContext.getControlPropertySet() and in any case you need a way to be able to tell whether an annotation is present or not (especially if you have marker annotations).

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