ReadinessMixin<T> mixin

Adds functionality to check and verify readiness. This usually constitutes completing some setup operation, but could also involve depending on another object's readiness and then taking an action.

Setup can be synchronous or asynchronous, which should be transparent to any code using this class.

To use ReadinessMixin in one of your classes, implement performInitialization and then, when appropriate, call markReady.

To use a class which adds ReadinessMixin, await the ready future, which returns a value of type T. T is the central object this resource produces once ready. If no such resource exists, choose void.

Synchronous usage:

class SyncResource with ReadinessMixin<SomeObject> {
  @override
  void performInitialization() {
    // Do setup...
    return SomeObject();
  }
}

// Elsewhere
final mySyncResource = SyncResource();
mySyncResource.initialize();

// Yet elsewhere
final SomeObject val = await mySyncResource.ready;

Asynchronous usage:

class AsyncResource with ReadinessMixin<SomeObject> {
  @override
  Future<SomeObject> performInitialization() async {
    // Do setup...
    return SomeObject();
  }
}

// Elsewhere
final myAsyncResource = AsyncResource();
myAsyncResource.initialize();

// Yet elsewhere
final SomeObject val = await myAsyncResource.ready;