leonr@cs.glasgow.ac.uk (Dr Ruben Leon) (06/12/89)
Could anyone direct me to some litterature on hypercard's computational model? Most of the papers I've seen relate to applications or are far too general on the theoretical aspects. Thanks.
dan@Apple.COM (Dan Allen) (06/13/89)
In article <12527.8906121343@emae.cs.glasgow.ac.uk> leonr@cs.glasgow.ac.uk (Dr Ruben Leon) writes: >Could anyone direct me to some litterature on hypercard's computational model? >Most of the papers I've seen relate to applications or are far too general >on the theoretical aspects. Thanks. Other than a few articles about hypertext in general (published in the IEEE and ACM publications), little has been written about HyperCard specifically, computational model-wise. The basic model of HyperCard is that there is a hierarchy of five major objects: stacks, backgrounds, cards, fields, and buttons. These objects have various properties, including scripts written in the HyperTalk language. Commands, usually known as messages, are sent either by the system (for mouse events, for example), or by the user (via handlers, or user procedures). These commands are then trapped along a message hierarchy and processed by the receiver. Optionally these messages can then be further passed along. HyperCard is an object-oriented environment, but it has some limitations. For example, a user cannot create a new object type with the same importance as the basic five. I believe, however, that systems which DO support arbitrary objects suffer due to performance considerations. HyperCard makes a good tradeoff, with very good performance. In addition to these basic features of the model of operation, HyperCard offers a set of bitmap paint tools, as well as fast text searching. Is this what you wanted to know about the computational model of HyperCard? Dan Allen HyperCard Team Apple Computer