Editing WoW:UI XML tutorial (section)

=== Basic Event Handling concepts ===

''If you are not used to event handled programming, read this section, otherwise you can skip right through it.''

Traditional programming style involves writing a program that has a start and finish. Execution starts at the beginning, and after following through the algorithm in the program, it eventually gets to the end.

Event handled programming is somewhat different. In this case, you create several, independent sections of code, with no clear start or finish. Each of these sections of code are designed to be executed in response to a certain event occurring. Such a section of code is called an ''event handler''. An event handler may get executed once, many times, or maybe even never. This kind of programming style is used whenever you want your code to interact with an external program, and do things in response to whatever that program is doing.

In the case of [[World of Warcraft]], the core game is external to the interface code. Whenever something happens in the game, it asks the interface code to respond to it, by calling one of the event handlers.