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CLASS LIBRARIES

A program which uses only the standard I/O functions developed for UNIX systems will be portable between many different platforms, but its poor user interface will be intolerable to most Macintosh users.  Since standard I/O programs usually do not use a Macintosh-style event loop, the non-portable part of Macintosh programs is often quite large.

A class library can be used to isolate all the machine-dependent code in a complex application, including the very style of the user interface.  Reliance upon standard- ized class libraries may eventually lead to portability of highly complex applications.

The Think Class Library* (TCL) distributed with Think C 4.0 offers an interesting and useful example.  The TCL includes the Application class which implements the usual Macintosh event loop.  The user derives a specialized class for his/her application, overriding certain methods.  In addition to simplifying the notoriously difficult task of writing Macintosh software, this library offers the potential for greater portability of Macintosh applications if/when versions for other platforms are made available.


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Think Class Library

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Think Class Library - p138

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p3