How exactly HelloWorldConfiguration and Environment get injected in the example

[DerekYangYC]

I'm new to dropwizard. In this example code:

public class HelloWorldModule extends AbstractModule {

  @Override
  protected void configure() {
    // anything you'd like to configure
  }

  @Provides
  public SomePool providesSomethingThatNeedsConfiguration(HelloWorldConfiguration configuration) {
    return new SomePool(configuration.getPoolName());
  }

  @Provides
  public SomeManager providesSomenthingThatNeedsEnvironment(Environment env) {
    return new SomeManager(env.getSomethingFromHere()));
  }
}

I don't quite understand why HelloWorldConfiguration could be injected as parameter and so does Environment

The document of Guice explicitly says the injection needs to go with annotation @Inject and the I can't find anyway in the source code of dropwizard-guice that use Automatic Injection.

Could anyone explain to my how this works?

[jhaber]

You can check out the documentation for ProvidesMethods here. These are special methods that create Guice bindings and the method parameters are implicitly injected by Guice.