java - Why Guice prevents from binding to Provider? -

java - Why Guice prevents from binding to Provider? -

recently, when played around google guice trying this:

@override protected void configure() { ... bind(provider.class).to(viewfactory.class); ... }

where viewfactory was:

public class viewfactory implements provider<sometype> {...}

of course, guice didn't allow me returing error:

1) binding provider not allowed. {stacktrace}

what reason why not possible bind provider?

i guess because provider interface special guice. in fact, internal machinery implemented in term of providers.

moreover, create ambiguities. if bindings providers possible:

bind(someclass.class).to(someclassimpl1.class); bind(new typeliteral<provider<someclass>>() {}).to(() -> new someclassimpl2());

then should guice inject here?

@inject otherclass(provider<someclass> someclassprovider) { ... }

should provider returns someclassimpl1 (because of first binding; remember, direct injections , provider injections interchangeable in guice) or should provider returns someclassimpl2 (because of sec binding)?

it redundant. because can inject someclass or provider<someclass> regardless of actual binding, can bind class provider:

bind(someclass.class).toprovider(() -> new someclassimpl()); // either of next work @inject otherclass1(provider<someclass> someclassprovider) { ... } @inject otherclass2(someclass someclass) { ... }

java dependency-injection guice