Appendix D - HyperCard
HyperCard
is a program which
allows the construction of other programs that have the Macintosh user-interface,
without the need for a large amount of underlying code to support the interface.
Macintosh programs are usually very complex: the nature of the interface requires
the writing of a large
amount of supporting code for most tasks, yet for the purposes of prototyping,
writing lots of program code can mean that the number of prototypes available for
testing is cut back owing to time limitations on the programmer. By providing
most of the background support work, HyperCard allows prototyping to take place
with more emphasis on the interface.
The metaphor for HyperCard is a
stack of cards, and a program written using HyperCard is known as a stack.
A stack consists of at
least one card, and can contain many thousands of cards. Each card
has a background, and a foreground, each which can
contain objects. The objects are buttons and fields,
and both of these can contain information, and program code known as scripts,
which are written in a language known as HyperTalk. If
HyperCard lacks a specific feature which a programmer would like to use, it is
possible to extend the functionality
of HyperCard using other programming languages, and writing external commands
or functions (called XCMDs and XFCNs). HyperCard lends itself to the construction
of simple databases, but undoubtedly its greatest use is in producing
stacks which look like fully-fledged Macintosh programs.
One of HyperCard's
weaknesses is that it is not particularly fast: scripts are interpreted not
compiled, and that it only has minimal colour support. However, these problems
aside, it is an excellent tool
for prototyping interfaces.
back to Appendix C. forward to Appendix E