Scoping Issues in Flex 2.0 Beta 3

I hadn’t faced a situation like this one in the previous builds of Flex 2.0, but I’m working with some new code. For some reason, I’m getting errors when I use the same variable name but different types for variables that are in different scopes. It’s a pain because its the “i” variable in a for loop. This issue seems to happen only within a single function.

private function scopingIssue():void
{
	if(this.width == 100)
	{
		for(var i:Number = 0; i 

Both those for loops are in different scopes, so they should work as different types, but I get the error, "A conflict exists with definition i in namespace internal". This is definitely a bug. Can someone remind me where to find the bug submission form?

About Josh Tynjala

Josh Tynjala is a frontend developer, open source contributor, bowler hat enthusiast, and karaoke addict. You might be familiar with his project, Feathers UI, an open source user interface library for Starling Framework that is included in the Adobe Gaming SDK.

Discussion

  1. JesterXL

    MTASC would bitch for the same reason in AS2. Basically, can’t re-declare the variable of the same name again, let alone to a different datatype. Although you and I see it as a different scope, the compiler see’s it as a function block with 2 local variables defined twice, which can you’d do.

    Submit the bug at the appropriate forum at labs.adobe.com.

  2. Josh Tynjala

    I made a similar function in MTASC, except I declared i as a String the second time. No errors. The if and else blocks should be different scopes, or at least that’s how other languages work.

  3. Ely Greenfield

    Actually, it’s not a bug. ECMAScript3 (Javascript, AS1) doesn’t support block level scoping, and ECMAScript4 (AS3) needs to be backwards compatible with it. So AS3 doesn’t have block level scoping. Which means that all variables declared inside a function are visible anywhere in the function. So you can’t declare the same variable twice with different types.

  4. Josh Tynjala

    Thanks Ely, good to know.

    I’m used to the idea of any {} block making a new scope. I know of some developers that will force a limited scope in other languages by just building an artificial block around a section of code. I suppose it would be a good way to force a garbage collection in C# or Java.

  6. Josh Tynjala

    The ECMAScript 4 specification defines a let keyword that may be used instead of var. This new keyword will allow you to keep scope inside a block rather than at the function level. Stayed tuned for it in a future update to ActionScript!