inject translator service in my service I am confused by this one. 

I want the translator service injected in my service. The closes thing I've found is this one: Drupal\Core\StringTranslation\TranslationManager; ( https://api.drupal.org/api/drupal/core!lib!Drupal!Core!StringTranslation!TranslationManager.php/class/TranslationManager/8.2.x) but it has no method "t" and it really makes emphasises to not use it's translate function, to use \Drupal\Core\StringTranslation\StringTranslationTrait; instead. But I can't inject this in my service, can I? (how?)

Ultimately, I just want to call t function in my own service.
It looks that there is no need to inject anything. Just use a "use" statement inside the class

class MyModuleService {
  use \Drupal\Core\StringTranslation\StringTranslationTrait;

  function a() {
    $this-&gt;t('should at least not complaint.');
  }
}