enbock / State-Value-Observer

export interface IOnChangeCallback<T> {

  (newValue: T): void;

}

export interface IObserverAdapter<T> {

  onChange: IOnChangeCallback<T>

}

export interface IObserver<T> {

  value: T

}

export default class Observer<T> implements IObserver<T> {

  protected adapter: IObserverAdapter<T>;

  protected current: T;

  constructor(initialValue: T, adapter: IObserverAdapter<T>) {

    this.current = initialValue;

    this.adapter = adapter;

  }

  public get value(): T {

    return this.current;

  }

  public set value(newValue: T) {

    this.current = newValue;

    this.adapter.onChange(newValue);

  }

}