0_question.js

angular.module( 'foo', [] )
  .service( 'Foo', service )
  .directive( 'foo', directive );
  
function service() { /* ... */ }

function directive() {
  return {
    controller : controller,
    controllerAs : 'fooCtrl',
    scope : {}
  }
}

function controller( Foo ) {
  this.name = 'my name is';
}

controller.prototype.setName = function setName( name ) {
  // i want to use Foo service here...
};

1_option.js

angular.module( 'foo', [] )
  .service( 'Foo', service )
  .directive( 'foo', directive );
  
function service() { /* ... */ }

function directive() {
  return {
    controller : controller,
    controllerAs : 'fooCtrl',
    scope : {}
  }
}

function controller( Foo ) {
  this.name = 'my name is';
  
  // feels dirty
  this._Service = Service;
}

controller.prototype.setName = function setName( name ) {
  this._Service.doSomething();
};

2_option.js

angular.module( 'foo', [] )
  .service( 'Foo', service )
  .directive( 'foo', directive );
  
function service() { /* ... */ }

function directive() {
  return {
    controller : controller,
    controllerAs : 'fooCtrl',
    scope : {}
  }
}

function controller( Foo ) {
  this.name = 'my name is';
  
  // performance and memory-efficiency sobs...
  this.setName = function setName( name ) {
    Service.doSomething();
  };
}