Avoid the with statement

One of the more confusing concepts to understand for people learning ActionScript 2.0 is using the with statement. Consider the following code that uses the with statement:

this.attachMovie("circleClip", "circle1Clip", 1);
with (circle1Clip) {
    _x = 20;
    _y = Math.round(Math.random()*20);
    _alpha = 15;
    createTextField("labelTxt", 100, 0, 20, 100, 22);
    labelTxt.text = "Circle 1";
    someVariable = true;
}

In this code, you attach a movie clip instance from the library and use the with statement to modify its properties. When you do not specify a variable's scope, you do not always know where you are setting properties, so your code can be confusing. In the previous code, you might expect someVariable to be set within the circle1Clip movie clip, but it is actually set in a timeline of the SWF file.

It is easier to follow what is happening in your code if you explicitly specify the variables scope, instead of relying on the with statement. The following example shows a slightly longer, but better, ActionScript example that specifies the variables scope:

this.attachMovie("circleClip", "circle1Clip", 1);
circle1Clip._x = 20;
circle1Clip._y = Math.round(Math.random()*20);
circle1Clip._alpha = 15;
circle1Clip.createTextField("labelTxt", 100, 0, 20, 100, 22);
circle1Clip.labelTxt.text = "Circle 1";
circle1Clip.someVariable = true;

An exception to this rule is, when you are working with the drawing API to draw shapes, you might have several similar calls to the same methods (such as lineTo or curveTo) because of the drawing API's functionality. For example, when you draw a simple rectangle, you need four separate calls to the lineTo method, as the following code shows:

this.createEmptyMovieClip("rectangleClip", 1);
with (rectangleClip) {
    lineStyle(2, 0x000000, 100);
    beginFill(0xFF0000, 100);
    moveTo(0, 0);
    lineTo(300, 0);
    lineTo(300, 200);
    lineTo(0, 200);
    lineTo(0, 0);
    endFill();
}

If you wrote each lineTo or curveTo method with a fully qualified instance name, the code would quickly become cluttered and difficult to read and debug.

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