ActionScript: The Definitive Guide

Creating Movie Clips

We usually treat movie clips just like data objects—we set their properties with the dot operator; we invoke their methods with the function-call operator (parentheses); and we store them in variables, array elements, and object properties. We do not, however, create movie clips in the same way we create objects. We cannot literally describe a movie clip in our code as we might describe an object with an object literal. And we cannot generate a movie clip with a movie clip constructor function, like this:

myClip = new MovieClip( );  // Nice try buddy, but it won't work

Instead, we create movie clips directly in the authoring tool, by hand. Once a clip is created, we can use commands such as duplicateMovieClip( ) and attachMovie( ) to make new, independent duplicates of it.

Movie Clip Symbols and Instances

Just as all object instances are based on one class or another, all movie clip instances are based on a template movie clip, called a symbol (sometimes called a definition). A movie clip’s symbol acts as a model for the clip’s content and structure. We must always have a movie clip symbol before we may generate a specific clip object. Using a symbol, we can both manually and programmatically create clips to be rendered in a movie.

A movie clip that is rendered on the Stage is called an instance. Instances are the individual clip objects that can be manipulated with ActionScript; a symbol is the mold from which all instances of a specific movie clip are derived. ...