My understanding is that a String object and a string literal are actually two very different types. While a string literal is a primitive type, a String object is a complex-type (or composite-type or reference) that wraps a primitive value – a string literal.

As you point out, the values undefined/null/0/"" are evaluated to false; any other value evaluates to true. An empty string literal would then evaluate to false. However, a String object with an empty string as a value would not evaluate to false, cause the object itself is not undefined, null, 0 or "".

A simple example to illustrate the point:

var objFoo:String = new String("");
var litFoo:String = "";

if(objFoo) {
trace("objFoo evaluates to true");
} else {
trace("objFoo evaluates to false");
}

if(litFoo) {
trace("litFoo evaluates to true");
} else {
trace("litFoo evaluates to false");
}

The result in the output panel is:

objFoo evaluates to true
litFoo evaluates to false

So, I believe the same rules apply to both the inline conditional and the if statement.

Cheers

PS: I'm looking forward to try your framework!