but I came across this post that uses an anonymous event handler function as part of a function literal within a function closure in order to “pass arguments to an event handler”
http://www.transcendentaxis.com/dthompson/blog/archives/19#more-19

Would you say that this could be an acceptable use case of an anonymous function?

Good catch (I updated the post).

Here is the info from the docs:
http://livedocs.adobe.com/flex/3/html/help.html?content=03_Language_and_Syntax_21.html

Activation Object is an object that “is created that stores the parameters and any local variables or functions declared in the function body. ”

“A function closure is an object that contains a snapshot of a function and its lexical environment. A function’s lexical environment includes all the variables, properties, methods, and objects in the function’s scope chain, along with their values. Function closures are created any time a function is executed apart from an object or a class.”

mike chambers

mesh@adobe.com

What you are referring to above is the “activation object” of anonymous functions. The activation object holds the local variables that were defined when the anonymous function was instantiated. Activation objects have been around since AS1.

It’s also worth noting that in almost every case, the use of an anonymous function in your code indicates an architectural problem. There are almost no real uses for anonymous functions – they are less efficient, much harder to debug, and far harder to grok when reading code.

However, today I stumbled upon a strange error related to their use. If you take this same code, and make FunctionClosureTest implement any interface, you will get compile errors in Flash CS4!

I am hoping this is just a bug in the beta version I was using, but if you try this code, I think you’ll see the same results I did.


package {
import flash.display.Sprite;
import ITest;

public class FunctionClosureTest extends Sprite implements ITest
{
public function FunctionClosureTest()
{
trace("Hello world");
}
public function method1():void
{
trace("method1");
}
}
}
class Foo
{
public function runFunction(f:Function):void
{
f();
}
}


And elsewhere define the interface…

package {
public interface ITest
{
function method1():void
}
}


CS4 will tell you that you have not implemented the interface appropriately, although the required methods are there. Even stranger still, the solution is to add another interface!

The following works just fine:

public class FunctionClosureTest extends Sprite implements ITest, IFixTheProblem