personally i am still in favor of going with the m2 way of doing things where
Component is generic, but from the looks of the discussion i think i may be
in the minority here. this kinda surprises me though because as i read the
original generic discussion it sounded like most people supported
Component<T>.
igor.vaynberg wrote:
>
> basically we feel this is a much cleaner way then what is 1.4m2. this
> is a call for confirmation/discussion from our user base.
>
1) i'm not sure i agree with this. i don't feel that just adding <Void> to
components that don't need their models makes things messy. i'd much rather
have the option to use generics whenever i need than to create extra classes
such as the 'GenericPanel', etc that have been mentioned. in fact i think
its alot messier to create more classes and to start changing method names
(getDefaultModel, etc) and then adding getModel to the classes that do use
generics.
2) the wicket web site now suggests the following code for generic
components:
@SuppressWarnings("unchecked")
public final T getModelObject()
{
return (T)getDefaultModelObject();
}
... but isn't the purpose of adding generic support to wicket to prevent the
need for unchecked casts? if we now have to place unchecked casts into our
code then we lose out on the strong type checking that generics are supposed
to provide. its not hard to imagine a case where one part of someone's code
calls setDefaultModelObject with the wrong type, and then later another part
of the code calls getModelObject and hits a class cast exception.
3) the Component class has several methods that return 'this' to allow for
method chaining. the problem here is that the generic components don't
override these methods with covariant returns, so if i do something like
formComponent.setVersioned(false).moreMethodCalls().chainedTogether() then
those chained methods can't use models because we've upcast our component to
something that doesn't have generic support. i guess the solution would be
to put these calls on separate lines, but it seems like a bit of a hassle
(i'm probably just being picky tho)
- craig
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