Hi,
I have a usecase where the current proposed generic Interface for IDataProvider
with upcoming v1.4 of Wicket would break the implementation concept working with
Wicket 1.3. The usecase needs different types for iterator + model. Example and
explanation are found below the vote:
VOTE:
[ ] IDataProvider<I,T>
[ ] Iterator<IModel<T>> , drop model
[ ] Leave as is.
Example:
new IDataProvider<Integer, Topics> {
public Iterator<Integer> iterator( int first, int count ) {
getForum().getTopics( first, count ); }
public int size() { getForum().getTopicsCount(); }
public IModel<Topics> model( Integer id ) { return new TopicsDetachableModel(
id ); }
}
The current proposed IDataProvider<T> would enforce model + iterator to be of
the same type, resulting in the above not working without hassle. I.e. either to
work without type safetey (always use Object to comply), or wrapping/querying
the type within iterator + model (which could cause time consuming lookups when
remote services are involved).
To get around this, there are 2 solutions:
- drop the 'model' method and have iterator return an Iterator<IModel<T>>
That would fit this usecase since the Model could just be wrapped within
iterator and no extra lookups would be necessary. Implementation code of
iterator might get a bit uglier, though.
- add a second type as shown with example above
Would lead to "redundant" type definitions for many usecases where iterator +
model actually return the same type.
I'd really like to see support for generics with these cases as well.
Best regards, --- Jan.
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