Multibinders and PrivateModules

[Árni Hermann]

Hi

Do you guys know if it's possible to expose a multibinder which is
bound in a private module?

I'm talking about something like the following...

In private module 1:
Multibinder<Source> multibinder = Multibinder.newSetBinder(binder(),
Source.class);
multibinder.addBinding().to(SourceImpl.class);
expose(??);

In private module 2:
Multibinder<Source> multibinder = Multibinder.newSetBinder(binder(),
Source.class);
multibinder.addBinding().to(SourceImpl.class);
expose(??);

In public module:
Multibinder<Source> multibinder = Multibinder.newSetBinder(binder(),
Source.class);
multibinder.addBinding().to(SourceImpl3.class);

With an injector which uses all of the moduels above, what would I
need to expose() in the private modules to be able to have Set<Source>
injected in a class which is bound in the public module?

Regards,
Árni Hermann

[limpb...@gmail.com]

Regretfully, multibindings cannot span injectors and therefore they
cannot span private modules. This sucks! But there's a (lame)
workaround. Expose a key in the private module, and multibind it in a
regular module:

Injector injector = Guice.createInjector(
new PrivateModule() {
public void configure() {
bind(Key.get(Source.class, named("one"))).to
(SourceImpl.class);
expose(Key.get(Source.class, named("one")));
...
}
},
new PrivateModule() {
public void configure() {
bind(Key.get(Source.class, named("two"))).to
(SourceImpl.class);
expose(Key.get(Source.class, named("two")));
...
}
},
new Module() {
public void configure() {

Multibinder<Source> multibinder
= Multibinder.newSetBinder(binder(), Source.class);

multibinder.addBinding().to(Key.get(Source.class, named
("one")));
multibinder.addBinding().to(Key.get(Source.class, named
("two")));
}
});

[Árni Hermann]

Yup, this sucks! :)

This (lame) workaround is simpler than the one I had in mind and looks
like it works just fine for my use case.

Thanks for the quick reply.

Regards,
Árni Hermann

[Matthew Madson]

I don't suppose this has gotten less lame over the years?

[Jonathan Leitschuh]

I've tried to offer a better solution that uses Kotlin. So maybe it has gotten better over the years finally?

https://github.com/google/guice/issues/906#issuecomment-500033982