Method chain

src/Deferred.java:820–827

Chains another Deferred to this one. This method simply ensures that whenever the callback chain in this is run, then the callback chain in other gets run too. The result handed to other is whatever result this currently has. One case where this is pa

(final Deferred<T> other)

  * @throws AssertionError if {@code this == other}.
   */
  public Deferred<T> chain(final Deferred<T> other) {
    if (this == other) {
      throw new AssertionError("A Deferred cannot be chained to itself."
                               + "  this=" + this);
    }
    final Chain<T> cb = new Chain<T>(other);
    return addCallbacks(cb, cb);
  }

  /**
   * Callback used to chain a deferred with another one.