Types of dependencies

During the registration stage, Odin puts some "invisible information" into dependency's prototype - marks to make the comprehension easier.

These information - not available from outside, are used to determine: how the dependency must be created and managed inside Odin and for how long it's supposed to be alive.

The current available marks are: singleton, discardable and custom. They can also be mixed to create custom behaviors.

Any dependency willing to be REGISTERED into Odin at any given time, must be a class. This rule does not apply to custom provided dependencies, see here.

By default ODIN has only two types of dependency: Injectable and Singleton.

  import { Injectable, Singleton } from '@philips/odin';

  @Injectable
  class MyInjectable {

    sayHi() {
      console.log(`Hi, I'm always a new potato!`);
    }
  }

  @Singleton
  class MySingleton {

    sayHi() {
      console.log(`Hi, I'm the same potato forever!`);
    }
  }

The main difference between these two types of dependencies, can be roughly described as the following:

• Whenever you inject an @Injectable, it will always be a new instance.
• Whenever you inject a @Singleton, it will always be the same instance. by container.

Remember that keeping complex states into singletons might be a bad idea.

For better understand dependencies definition, see here.