ActionScript for Flash MX: The Definitive Guide, Second Edition

arguments.length Property

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ActionScript Language Reference

// Now call formatTitle() and formatBody() from formatPage()

formatPage();

// Displays: true and true

// Then call formatTitle() directly

formatTitle();

// arguments.caller will be null. Displays: false

We can use caller to execute or identify a calling function and to check whether a func-

tion was called directly or by another function.

Usage

Note that in Netscape 4, JavaScript’s arguments.caller refers to the Arguments object of

the calling function, not the calling function itself. In JavaScript,

arguments.caller is depre-

cated as of version 1.3, and it is not supported by Internet Explorer or later versions of

Netscape.

Bugs

Macromedia’s initial documentation for Flash MX incorrectly claims that arguments.caller

refers to the calling function’s Arguments object. It refers, in fact, to the calling function

itself, not the caller’s Arguments object.

Example

The following code shows a function that aborts itself when called directly, ensuring that it

is only called by a larger routine:

function subFunction () {

if (arguments.caller = = null) {

return "Function cannot be called directly.";

}

// proceed with function...

}

See Also

arguments.callee

arguments.length Property

the number of parameters passed to an argument

Flash 5

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