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7 Event Dispatching with SERVE-EVENT

It is common to have multiple activities simultaneously operating in the same Lisp process. Furthermore, Lisp programmers tend to expect a flexible development environment. It must be possible to load and modify application programs without requiring modifications to other running programs. CMUCL achieves this by having a central scheduling mechanism based on an event-driven, object-oriented paradigm.

An event is some interesting happening that should cause the Lisp process to wake up and do something. These events include X events and activity on Unix file descriptors. The object-oriented mechanism is only available with the first two, and it is optional with X events as described later in this chapter. In an X event, the window ID is the object capability and the X event type is the operation code. The Unix file descriptor input mechanism simply consists of an association list of a handler to call when input shows up on a particular file descriptor.

• Object Sets
• The SERVE-EVENT Function
• Using SERVE-EVENT with Unix File Descriptors
• Using SERVE-EVENT with the CLX Interface to X
• A SERVE-EVENT Example