Flash Actionscript Actionscript 2

Understanding Function Scope in ActionScript 2.0

Are you struggling to call a nested function in ActionScript 2.0? You’re not alone. This issue often confounds developers who are transitioning from other programming languages. In this post, we’ll tackle the intricacies of function declarations in ActionScript and provide you with solid solutions to effectively call your functions.

The Problem at Hand

Let’s break down the scenario. You have a function named parentFunction() that contains another function called callMe(). The goal is to call callMe() within another part of your code, such as an onRelease event handler. Here’s the core of the issue based on the provided code:

//Function Declarations
function parentFunction()
{
    function callMe()
    {
        textField.text = "lawl";
    }
}

When you try to call callMe() from an on(release) event, none of the following calls work:

on(release)
{
    callMe(); // doesn't work
    parentFunction().callMe(); // doesn't work
    parentFunction.callMe(); // doesn't work
}

Solution: Understanding Function Scope

Why It Doesn’t Work

Your attempt to call callMe() fails because, in ActionScript 2.0, functions have their own scope. When you declare callMe() inside parentFunction(), it becomes a private function. This means that callMe() cannot be accessed from outside its defining function.

How to Define Function Scope Properly

To successfully call a nested function, you need to adhere to a couple of guidelines:

Function Declaration Outside Another Function: Generally, if you want a function to be accessible from multiple locations, define it outside of its parent function.
```
function callMe()
{
    textField.text = "lawl";
}

function parentFunction()
{
    // Other code...
}
```
Using Method Returning Objects: If encapsulating the function in the parent function serves a purpose, you need to set up the right architecture so that the nested function is accessible when needed. You would typically manage complex relationships between functions using objects.
- In JavaScript, similar methodologies employ prototypes for methods. However, ActionScript has its own conventions.

Recommended Resources

For a better understanding of how functions can be structured in JavaScript, check out this tutorial on JavaScript Objects.
To grasp more nuanced concepts of functionality in ActionScript, visit the Adobe DevNet documentation.

Final Thoughts

In summary, it’s paramount to understand that nested functions in ActionScript 2.0 are scoped to their enclosing functions. If you require broader access to such functions, it’s advisable to define them in the global scope or leverage object-oriented principles to create proper access controls. If you’re still feeling confused by the differences between private and public functions, the linked article on JavaScript’s public/private function debate may provide additional clarity.

Happy coding, and don’t hesitate to reach out if you have questions or need further assistance!