Abstract

consistent fashion. Another reason arises from the initial motivation of component-oriented programming, incrementality: the new component should not duplicate functionality of the old one. Thus there must be some way for the new component to "inherit" all unmodified behaviour but substitute its own behaviour where appropriate. In traditional, statically typed, class-based object models, where component interaction at run-time is solely based on message sending, this is impossible to achieve without compromising reuse ([1]). An interesting alternative is the concept known as delegation ([5]). An object, called the child, may have references to other objects, called its parents. Messages for which the message receiver has no matching method are automatically forwarded to its parents after binding their implicit self parameter to the message receiver. Thus, all subsequent messages to self will be addressed to the message receiver, allowing it to substitute its own behaviour for par

Citations