22 The Redisplay Mechanism

The redisplay mechanism is one of the most complicated sections of SXEmacs, especially from a conceptual standpoint. This is doubly so because, unlike for the basic aspects of the Lisp interpreter, the computer science theories of how to efficiently handle redisplay are not well-developed.

When working with the redisplay mechanism, remember the Golden Rules of Redisplay:

1. It Is Better To Be Correct Than Fast.
2. Thou Shalt Not Run Elisp From Within Redisplay.
3. It Is Better To Be Fast Than Not To Be.

• Critical Redisplay Sections
• Line Start Cache
• Redisplay Piece by Piece