Status of project?

[roni-frantchi]

Hi @adriancarriger .
Been looking for something like this.. Thanks.

Got a couple of questions:

1. What's the status of the project? Do you still maintain it or has it come to a halt?
2. How will this work with lazy loaded modules?

[adriancarriger]

Hi @roni-frantchi,

I started this module to hide the boilerplate that allows you to create modules that don't require the .forRoot method, but still create a single instance that can be shared inside an app.

angular-provide-once does this for simple services, but there are issues with more complex setups that involve opaque tokens, deep dependancies trees, and AOT. It's still completely possible to implement this manually. Here's how:

Ng Module

The goal is to create a module (that doesn't use .forRoot) that your users can import. This module needs to include a special provider that will be created in a later step. The module might look something like this

@NgModule({
  providers: [
    YOUR_SERVICE_PROVIDER
  ]
})
export class SomeModule { }

Simple example

To create this special provider you'll first need to create a factory that your provider will use.

Factory

export function YOUR_SERVICE_PROVIDER_FACTORY(
    yourService: YourService) {
  return yourService || new YourService();
}

Provider

export const YOUR_SERVICE_PROVIDER = {
  // If there is already a YourService available, use that. Otherwise, provide a new one.
  provide: YourService,
  deps: [[new Optional(), new SkipSelf(), YourService]],
  useFactory: YOUR_SERVICE_PROVIDER_FACTORY
};

This setup will go up the dependency tree and check if YourService is already provided. If it's not, it will create it inside the factory where you see new YourService();.

I got this idea reading through the Angular Material 2 Code

It looks like the Angular team might be considering integrating a similar behavior into the core code.

Complex example

Here is a more complex example that requires multiple dependancies including an opaque token. Let me know if you have any questions.

[roni-frantchi]

Thank you so much @adriancarriger !
Will definitely look into it.