The generics support in 5.1 is pretty limited. I've implemented a patch for 5.2
that should solve your problem which will be checked into the trunk soon. Since
you've provided a good use case I'll add it to the unit tests when I get to a
computer. I'm not sure that it will be back-ported to 5.1 (is generics support
a feature or bug fix?)
-- Josh
On Sep 10, 2010, at 2:17 PM, danrwilliams <dan_r_willi...@yahoo.co.uk> wrote:
>
> Hi,
>
> I am trying to standardise the way our developers code a page class that
> uses a Grid component. Part of this process is defining an interface that
> contains the get/set methods for the property used in the row parameter of
> the Grid component.
>
> Since the data used in any Grid in our project will always extend from a
> specific super-type, I have created a bounded generic interface to give type
> safety to the get/set methods in the page class.
>
> The problem is, Tapestry 5.1.0.5 doesn't seem to honour this.
>
> I'll try to illustrate..
>
> Our code looks something like this;
>
> class MyPageClass implements MyInterface<MyGridRowType> {
> ...
> ...
> @Override
> public MyGridRowType getRow() {...}
>
> @Override
> public void setRow(MyGridRowType row) {...}
>
> ...
> }
>
> interface MyInterface<T extends GridRowSupertype> {
>
> T getRow():
>
> void setRow(T row):
> }
>
> interface GridRowSupertype {
> String getStringA();
> }
>
> class MyGridRowType implements GridRowSupertype {
>
> @Override
> public String getStringA() {...}
>
> public String getStringB() {...}
> }
>
> Now, in the Grid component in our template file, if I try to use
> '${row.stringb}' Tapestry throws an exception saying;
>
> "...Class GridRowSupertype does not contain a property named 'stringb'...
> ...Available properties: stringa..."
>
> Even though this is technically correct, Tapestry is referencing the
> super-type and not the sub-type supplied by the page class. The return type
> on the getRow() method in the page class is MyGridRowType, which does
> contain the required method (getStringB).
>
> I have confirmed this by simply removing the interface 'MyInterface' from
> the page class and everything works fine.
>
> Any suggestions?
>
> Thanks,
> Dan
>
> --
> View this message in context:
> http://tapestry.1045711.n5.nabble.com/Generics-problem-with-Grid-row-parameter-tp2835598p2835598.html
> Sent from the Tapestry - User mailing list archive at Nabble.com.
>
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