Feature Request Guice automatically builder pattern

[Kyle Roush]

I would like to use a builder (preferably auto-value)  with Guice.

Guice can find constructors annotated with @Inject but those can be cumbersome to maintain and I would like to move to a builder pattern and have that be automatically found.

so the current way is like

class ExampleA {

  ...

  @Inject
  public ExampleA(A a, B b, ...) {

  }

  ...

}

But I would like to be able to

@ProvidedBy(builder = Builder.class) // or some way to let know guice to know what is the thing that builds it
@AutoValue
class ExampleB {
  ...

  @AutoValue.Builder
  public abstract static class Builder {

     public abstract Builder setA(A a);


     public abstract Builder setB(B a);

     ...

     public abstract ExampleB build();
  }


}

Right now the only way i can think of how to use a builder pattern with Guice is to have a provides method int he module and have all the possible inputs injected in to the method of the provides which can still be very annoying to maintain

I am open to different ideas on how to link the builder and real object.

[Thomas Broyer]

Would that work?

@ProvidedBy(AutoValue_ExampleB.Builder.class)
@AutoValue
abstract class ExampleB {
  …


  @AutoValue.Builder
  abstract static class Builder implements Provider<ExampleB> {
    @Inject abstract Builder setA(A a);
    @Inject abstract Builder setB(B b);
    …
    abstract ExampleB get();
  }
}

That said: AutoValue has been designed for "value objects", and you're kind-of "abusing" it here as a "generic generator of builders".

(I also don't see how this is less cumbersome to maintain than a constructor; where your IDE can generate the constructor argument from a declared final field).