In Visual Object - Oriented Programming

A visual shell, such as the Apple Macintosh Finder, is a direct manipulation interface to a le system. Although such systems are easy to use, they are are diicult to program, especially for non-programmers. This paper introduces Pursuit, a visual shell design that combines visual program speciication, visual language representation and object-oriented techniques, to address some of the problems of visual shells, and discusses some of the issues relevant to making Pursuit's approach viable. First, Pursuit extends the concept of a concrete, directly manipulable object to all interface objects, so that the output of any utility can be selected as input (i.e., piped) to other utilities. Second, Pursuit incorporates a Programming by Demonstration (PBD) system into the interface. This enables non-programmers to construct programs by manipulating representations of le system objects, such as les and folders, directly in the interface. Finally, Pursuit introduces an object speciic, state-based visual representation language for programs. Programs are static, editable representations of objects and behaviors that reeect the interface. Hence, Pursuit provides a uniform model { that of object and behavior { for users to learn in order to understand, navigate and program in Pursuit.