Events, messages, and handlers
A key component
to creating powerful, useful scripts is an understanding of the concepts
and functionality of events, messages, and handlers. Understanding the
order in which events and messages are sent and received will help
you determine exactly when specific scripts or parts of scripts
should run. It will also help you debug scripts when specific actions
are not occurring when you expect them to occur.
When a movie plays, the following occur:
Events occur in response to either a system or user-defined
Messages that correspond to these events are sent to the
scripts in a movie.
Handlers within scripts contain the instructions that run
when a specific message is received.
The name of an event corresponds to the name of the message it
generates, and the handler that handles the event corresponds to
both the event and the message. For example, when the event named mouseDown occurs,
Director generates and sends to scripts a message named mouseDown,
which would in turn be handled by a handler named mouseDown.