# Initializing movie clips with class assignment

To make sure that the class assignment occurs before the symbol appears on Stage, you can place the `registerClass` method on the first frame of the movie clip within an `#initClip/#endInitClip` code block, as shown below.

    // On frame 1 script of the movie clip with identifier string "symbolID":
    #initClip
    	Object.registerClass("symbolID", className);
    #endInitClip

In fact, this is exactly what is done automatically (by the compiler) when you assign a class with the ClassName field in the Linkage Properties dialog. The compiler inserts, on the first frame of the movie clip to which you assigned the class, an `#initClip`/`#endInitClip` code block containing the apprpropriate Object.registerClass() method call.

For example, suppose you have a movie clip with a symbol linkage ID name of `Ball`, and you entered `animation.Spin` in the ClassName field in the Linkage Properties dialog for that symbol. Upon export to SWF, the compiler would add the following ActionScript to the first frame of the `Ball` movie clip.

    #initClip
    	Object.registerClass("Ball", animation.Spin);
    #endInitClip

For more information about `#initClip` and `#endInitClip` see .

Controlling order of execution for class assignmentsYou place actions to assign a class on the first frame of a movie clip symbol. In the normal order of execution in ActionScript, the actions assigning the class would be executed at the end of the frame. However, in most circumstances you will want the class assignment to be executed in front of the frame, before the movie clip is instantiated, so that properties of the class are enabled as soon as the movie clip appears. In order to execute the class assignment actions in front of the frame, you must add the tags `#initclip` and `#endinitclip` at the beginning and end of the actions.

To execute a class assignment in front of the frame in which the code is placed:

- Use the following syntax.

    #initclip
    function Constructor(value1, value2, value3){
    this.property1 = value1;
    this.property2 = value2;
    this.property3 = value3;
    }
    #endinitclip