Interfaces

An interface has a name and consists of a set of message declarations and one or more constructor declarations. We do not allow (state) variable declarations² at present because the idea is to support specifications in the absence of state information.

An interface defines a type, a set of messages (services) that the object can handle and constructors for creating new objects of the type. Message declarations can be overloaded.

The ReadWrite interface described in section 2 has two messages Read(), Write(int i) and a constructor ReadWrite(). An object created using the constructor ReadWrite() is of ReadWrite type.