Gem #28: Changing Data Representation (Part 2)

摘要

Part 2, Efficiency Considerations.Last week, we discussed the use of derived types and representation clauses to achieve automatic change of representation. More accurately, this feature is not completely automatic, since it requires you to write an explicit conversion. In fact there is a principle behind the design here which says that a change of representation should never occur implicitly behind the back of the programmer without such an explicit request by means of a type conversion.