Rename to postConstruct all methods decorated with the @postConstruct() decorator

[paul-marechal]

• Rename to postConstruct all methods decorated with the @postConstruct() decorator.
• Type all those methods as () => void.

There are a lot of inconsistencies when it comes to this post-constructor callback method. most of the time the method is called init, but sometimes configure, or initialize. I would prefer to call it postConstruct as it better describes what the method is meant for, but since init is most commonly used I would be OK with renaming to this instead.

Inversify's postConstruct exist because when it tries to create the instances for our bindings, it has to call the constructor before it can inject properties (if any). See the following example:

@injectable()
class Component {

  @inject(SomeService)
  protected _service: SomeService;

  constructor() {
    // this._service is undefined here!
  }

  @postConstruct()
  protected postConstruct(): void {
    // this._service got injected, we can use it.
  }
}

A problem in our code base is that some of those postConstruct functions return promises. Inversify won't wait on them, as the instance creation step assumes everything happens synchronously. This means that more often than not, by the time our asynchronously-post-constructed services are injected, dependents might try to call into uninitialized properties...

[tsmaeder]

@paul-marechal the problem with returning promises seems much more severe than the naming. Did you open an issue?

[paul-marechal]

Naming is just for consistency/clarity but the asynchronous issue is an actual problem indeed. I'll open an issue just for it.

#10788

[msujew]

They are now all called init, see #12425.