Guice: is it possible to inject modules?

sxc731 picture sxc731 · Mar 31, 2011 · Viewed 17.6k times · Source

I have a Module that requires some Depedency. Is there a way Modules themselves can be injected? I realize this is a bit of a chicken and egg situation...

Example:

public class MyModule implements Module {

    private final Dependency d_;

    @Inject public MyModule(Dependency d) {
        d_ = d;
    }

    public void configure(Binder b) { }

    @Provides Something provideSomething() {
        // this requires d_
    }
}

I suppose in this case the solution would be to turn the @Provides method into a full-fledged Provider<Something> class. This is clearly a simplified example; the code I'm dealing with has many such @Provides methods so cutting them each into individual Provider<...> classes and introducing a module to configure them adds a fair amount of clutter - and I thought Guice was all about reducing boilerplate clutter?

Perhaps it's a reflection of my relative noobyness to Guice but I've come across a fair few cases where I've been tempted to do the above. I must be missing something...

Answer

ColinD picture ColinD · Mar 31, 2011

@Provides methods can take dependencies as parameters just like parameters to an @Inject annotated constructor or method:

@Provides Something provideSomething(Dependency d) {
   return new Something(d); // or whatever
}

This is documented here, though perhaps it could be made to stand out more.