System Handles

The class <system-handle> is used to trace/debug/display splats (or any other function) in the system. One could think of a system handle as a ``global variable'' which specify what to do when tracing, debugging, logging or displaying data associated with a splat (or any other function) in your system. One could then turn on or off any of these features while the corresponding splat (function) is running.

The class <system-handle> has the following public fields: ^3.5

  (name           (self <system-handle>))
  (trace?         (self <system-handle>))
  (trace-window   (self <system-handle>))
  (log?           (self <system-handle>))
  (debug?         (self <system-handle>))
  (display-server (self <system-handle>))

The fields trace?, log?, and debug? specify whether tracing, logging, or debugging are ON or OFF respectively. The field trace-window specify the window to which the trace output is directed. The field display-server specify the ``server'' to which the system-handle sends data to be ``displayed'' (more latter). We will explain the different system handle facilities later.

A global list of the system handles available is kept. The function

 (get-<system-handle> name)

returns the system handle whose name is name. To define a system handle one has to invoke the method start,

 (start (make <system-handle> name: name))

Next we present the different facilities associated a system handle.