In my angular project i want to split my services into interfaces (abstract classes) and implementations (implementing those interfaces). E.g. from
import { Injectable } from "@angular/core";
import { ImpyService } from "./implementation/impy.service";
@Injectable({
providedIn: 'root',
})
export class AggyService {
doSomething() {
// ...
}
}
to
// "Interface"..
@Injectable({
providedIn: 'root'
})
export abstract class AggyService {
abstract doSomething();
}
// & "Implementation..
@Injectable()
export class ImpyService implements AggyService{
doSomething() {
// do something
};
}
Now, since AggyService is abstract it can only be used the the injection key and i have to specify the implementation as the injection value/provider and add it to the providers-property in an NgModule, Component, or Inject() it 'directly'.
E.g. when wanting it to be globally available in my app.module.ts
@NgModule({
// ...,
providers: [
{ provide: AggyService, useClass: ImpyService }
]
})
export class AppModule { }
But - as far as i know - this prevents tree-shaking as the service now is imported in app.module.ts.
I found, that i can specify the provider in the @Injectable()-decorator like so
@Injectable({
providedIn: 'root',
useClass: ImpyService
})
export abstract class AggyService {
abstract doSomething();
}
This works (for now), but also, seems to be undocumented (e.g. see https://angular.io/api/core/Injectable).
I really don't want to stick to undocumented stuff, but i don't know how to do this another way.
How to go about this?
As i just wanted to create an issue for this, i found, that this already exists and seems to be added to the documentation somewhere in the future...