Hi Andrea,
thx for the reference. Michael's proposal is awesome and I'm I think we
should go for a better model interface hierarchy. But this proposal, of an
IReadyOnlyModel as an IModel extension, wasn't discussed. My point is that
we can provide an interface "designed" to provide a function as a model and
have a little impact on existent Wicket projects at the same time. Just to
be clear, I'm 1+ for Michael's proposal, but if don't pass, I would be 1+
for this proposal.
Hi Emond,
> Your proposal will not work because Java does not resolve functional
> interfaces to subtypes of the target type. For example, take the Label
> constructor:
I know, and that is just a good thing. Take TextField for example, we don't
want it constructed with a function as a model:
new TextField("id", Bean::getMethod())
this proposal is correctly preventing the user from assigning a read-only
model to a component designed to write on it.
> In Wicket 8 this works, because IModel is a functional interface, so Java
> knows how to convert a method taking no arguments and returning a double
into
> a IModel<Double> by mapping that method to getObject().
Sure, and it's our job to provide good a API allowing the user to benefit
from Java 8 features *where it does make sense*. A good set of constructors
for a Label would include:
public Label(String id, IReadyOnlyModel model){ ... }
Cheers
Pedro Santos
On Mon, Apr 10, 2017 at 3:27 AM, Emond Papegaaij <[email protected]
> wrote:
> Hi Pedro,
>
> Your proposal will not work because Java does not resolve functional
> interfaces to subtypes of the target type. For example, take the Label
> constructor:
>
> public Label(String id, IModel<?> model)
>
> I would like to use this constructor as follows:
>
> new Label("id", Math::random)
>
> In Wicket 8 this works, because IModel is a functional interface, so Java
> knows how to convert a method taking no arguments and returning a double
> into
> a IModel<Double> by mapping that method to getObject().
>
> With your proposal, this code needs to be changed to:
>
> new Label("id", (IReadOnlyModel<Double>) Math::random)
>
> So time ago, we tried to make IModel extend a ReadOnlyModel. In that case,
> it
> would work, but the change did not work out very well.
>
> Best regards,
> Emond
>
> On vrijdag 7 april 2017 12:45:53 CEST Pedro Santos wrote:
> > Hi devs,
> >
> > IModel isn't an interface designed to provide a function, it's rather an
> > interface designed to provide and manipulate (setObject and detach
> methods)
> > internal state.
> >
> > IMO a better alternative to benefit from Java 8 features would be to move
> > the FunctionalInterface annotation to an interface that actually is
> > designed to provide one function.
> >
> > I propose that we add a new interface extending IModel to provide this
> > functional interface, instead of to misplace it in an interface made for
> > objects with internal state.
> >
> > e.g.
> >
> > @FunctionalInterface
> > interface IReadyOnlyModel / IModelFunction / IFunction extends from
> IModel{
> >
> > default void setObject(final T object)
> > {
> > throw new UnsupportedOperationException("unsuported");
> > }
> >
> > default void detach()
> > {
> > throw new UnsupportedOperationException("unsuported");
> > }
> >
> > }
> >
> > Cheers
> >
> > Pedro Santos
>
>
>
