I forgot to upload the @GwtCreate annotation. You can find It here https://gwt-review.googlesource.com/#/c/4111/ Regards
- Andrés El viernes, 16 de agosto de 2013 06:30:15 UTC-3, Andrés Testi escribió: > > I've been working on a prototype inspired by Ray Cromwell's proposal for > @GwtCreate parameters, borrowing some ideas from Scala implicit macros. I > apologize for not to post this in the "Possible GWT.create() Improvements" > thread, but this message is too long to be only a comment. > You can check my patch at https://gwt-review.googlesource.com/4110. This > prototype has passed many JUnit tests cases and works fine (only fails > JEnumTypeTest after my last pull, I don't know why). Devmode also works. > This proposal differs from Ray's original idea in that @GwtCreate is a > parameter annotation instead of a method annotation. Later I will justify > this decision. > This new proposal consists on rewriting methods adding a trailing implicit > parameter of type o for each parameter annotated with @GwtCreate. > GwtCreateFactory is a hidden interface used by the compiler: > > interface GwtCreateFactory { > <T> T create(); > } > > When the compiler finds a code-gen method like > > Foo createFoo(@GwtCreate final Class<? extends Foo> fooType) { > return GWT.create(fooType); > } > > it is rewritten as > > Foo createFoo(final Class<? extends Foo> type, GwtCreateFactory > fooType$factory) { > return fooType$factory.create(); > } > > IMPORTANT: > ---- The @GwtCreate parameter requires to be final. > ---- This proposal doesn't require constant evaluation expression. The > final modifier is required to disable non reproductible side effects. > > At method call site, an invocation like > > Foo foo = createFoo(SubFoo.class); > > is rewritten as > > class SubFoo$GwtCreateFactory implements GwtCreateFactory { > @Override public <T> T create() { > return GWT.create(SubFoo.class); > } > } > > Foo foo = createFoo(SubFoo.class, new SubFoo$GwtCreateFactory()); > > Just like Scala implicit parameters, @GwtCreate can fight against type > erasure and subtyping > > interface FooCreator { > > <T extends Foo> T create(@GwtCreate Class<T> fooType); > } > > class FooCreatorImpl extends FooCreator { > > <T extends Foo> T create(@GwtCreate final Class<T> fooType) { > return GWT.create(fooType); > } > } > > code-gen constructors are supported too > > class CreateByConstructor<T extends Foo> { > > final T instance; > > public CreateByConstructor(@GwtCreate final Class<T> fooType) { > instance = GWT.create(fooType); > } > } > > Again, as in Scala implicit parameters, nesting is allowed > > class Foo {} > class SubFoo extends Foo {} > > <F extends Foo> F createFoo(@GwtCreate final Class<F> fooType) { > return GWT.create(fooType); > } > > <S extends SubFoo> S createSubFoo(@GwtCreate final Class<S> subFooType) { > return createFoo(subFooType); > } > > The decision to locate @GwtCreate on parameters was taken to support mixed > code-gen methods > > <F extends Foo, B extends Bar> > void fooBarCreator(@GwtCreate final Class<F> fooType, @GwtCreate final > Class<B> barType) { > foo = GWT.create(fooType); > bar = GWT.create(barType); > } > > Note that the @GwtCreate class parameters aren't replaced by > GwtCreateFactory as was originally suggested by Ray Cromwell. This provides > access to actual parameters. > > Class<T> storedType; > T instance; > > void createFoo(@GwtCreate final Class<T> type) { > storedType = type; > instance = GWT.create(type); > } > > * Upcoming improvements: > > 1) Support for explicit generators > > @GwtCreate(generator = FooGenerator.class) > > We should forbid assignation between parameters that differs in > @GwtCreate signature > > Foo createFoo(@GwtCreate(generator = FooGen.class) final Class<? > extends Foo>) {...} > > // This will fail > Foo forbiddenNesting(@GwtCreate(generator = BarGen.class) final > Class<? extends Foo> fooType) { > return createFoo(fooType); > } > > 2) Multiple parameters for GWT.create() by means of @GwtCreate.Param > > <U, O> UiBinder<U, O> createBinder( > @GwtCreate(generator = UiBinGen.class) final Class<U> uiType, > @GwtCreate.Param final Class<O> ownerType) { > > return GWT.create(uiType, ownerType); > } > > @GwtCreate.Params must respect the same kind of signature rules than > @GwtCreate, and a strict order of invocation > > // Good ordering > Foo createFoo( > @GwtCreate final Class<? extends Foo> fooType, > @GwtCreate.Param final Class<?> arg1, > @GwtCreate.Param final Class<?> arg2) { > return GWT.create(fooType, arg1, arg2); > } > > // Bad ordering, this will fail > Foo createFoo( > @GwtCreate final Class<? extends Foo> fooType, > @GwtCreate.Param final Class<?> arg1, > @GwtCreate.Param final Class<?> arg2) { > > return GWT.create(fooType, arg2, arg1); > } > > To allow mixed multiple code-gen parameters, we would bind main > parameters by name > > <F extends Foo, B extends Bar> > void mixedMultiple( > @GwtCreate final Class<F> fooType, > @GwtCreate.Param("fooType") final Class<?> fooArg, > @GwtCreate final Class<B> barType, > @GwtCreate.Param("barType") final Class<?> barArg) > > 3) Support for GWT.create(this.getClass()) ? not exactly, but... > > Explicits generators can eliminate the issue of the unique generator > per class hierarchy. An aditional boolean parameter for @GwtCreate would > mitigate the code size issue > > abstract class UiBinderComposite extends UiBinderComposite { > > public UiBinderComposite() { > UiBinder<Widget, UiBinderComposite> binder = > createBinder(getClass()); > } > > private static UiBinder<Widget, UiBinderComposite> > createBinder(@GwtCreate( > // The explicit generator knows when to stop the code > generation > generator = UiBinderCompositeGenerator.class, > > // this.getClass() is disallowed by default. > allowsThisClass = true) > final Class<? extends UiBinderComposite> type) { > > return GWT.create(type); > } > } > > Only API authors should treat with GWT.create(). API users should stay > isolated by means of code-gen methods. > > > I can formalize all of these in a document if you agree. > > Thanks for your attention! > > - Andrés > -- http://groups.google.com/group/Google-Web-Toolkit-Contributors --- You received this message because you are subscribed to the Google Groups "GWT Contributors" group. To unsubscribe from this group and stop receiving emails from it, send an email to google-web-toolkit-contributors+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/groups/opt_out.
