Implementation Inheritance and Delegation in p6i (2)

• A subclass may delegate some methods.

  bbufli = class implements bbufl extends bbuf_basei
      slot l:lock
      delegate lock, free to l
    new = method(n:int) replies(self{empty.free})
      b:self := super(n); b.l := lock!new(); reply(b!{empty.free})
    end new
  end bbufli
  

  Above is equivalent to the following:

  bbufli = class implements bbufl extends bbuf_base
      slot l:lock
    new = method(n:int) replies(self{empty.free})
      b:self := super(n); b.l := lock!new(); reply(b!{empty.free})
    end new
    lock = method({*.free}b:self{-.locked}) b.l!{-.locked} end lock
    free = method({*.locked}b:self{-.free}) b.l!{-.free} end free
  end bbufli