"Parents before Child" concept for Component Rendering does not allow different rendering in subclasses

• Key: TAP5-51
• Type: Bug
• Status: Closed
• Resolution: Invalid
• Priority: Major
• Assignee: Howard M. Lewis Ship
• Reporter: Fritz Pröbstle

Description

I subclassed GridPager ( public class MyGridPager extends GridPager) to implement another pager visualisation.
After creating a MyGrid (public class MyGrid extends Grid) which uses MyGridPager and copying Grid,tml to MyGrig.tml ist was ready to test.

Start.tml:
        <t:mygrid source="tl" row="treffer" rowsPerPage="5">
               <t:parameter name="regnrcell">
                 <t:pagelink page="marke2" > ${treffer.regnr}</t:pagelink>
            </t:parameter>
        </t:mygrid>

It runs fine - but I got the "old" ,default Visualiation *AND* the new one. It is a result of the "Parents before Child" concept .
First the Parent creates its visualisatrion the my Child createy its new visualisation.

Subclasses can not decide of they want to call the implemetation of their parent or not.

Why is this implemented like this?
Why call parent implemtation at all, the child could do this explicit by calling super.XXX.( I know Annotations may make this more complex)


Can you help ?

Comments

[Howard M. Lewis Ship]

There are complex issues at foot here, and there may not be any single solution that meets all needs in all cases.

The super approach is not valid: the super class methods may be private, or have different parameters or return types.

[Howard M. Lewis Ship]

My approach here will be that if the child class *overrides* a method of the parent, then the overridden method will be invoked only by the parent class, not the subclass.

[Fritz Pröbstle]

The *override* functionality works fine if all classes base and subclass(es) are in the same package-then
the overriden function is called for subclass only.

If base and subclasses are in *different* packages only the base class function is called. ( It seams as if tapestry did not "see" the overwritten one.

This really seams to be the problem, because if you
specify the function to be "protected" (at least) tapestry can "see" it and calls the correct one.

This workaound can be done id source is available for the base class(es) and does not work if I want to subclass
core-components.( And naturally this is doen in another package, so this error prevents my to use the new *Overridíng* feature)

[Howard M. Lewis Ship]

Still don't think there's a bug here, and your comment about different packages ... are you sure the overridden methods are protected or public?