Like Javascript, previous versions of Actionscript had eval(). The latest, Actionscript 3.0, does not.
Peter Fisk's Smalltalk and Lisp in Flex is a treasure in its own right. But in light of Adobe taking away eval(), the desire to have some kind of language interpreter at runtime goes exponential.
I could do with evaluating Actionscript at runtime. There are legitimate reasons to have a fairly-Javascript-like language for customizing interactive applications, although Lisp and Smalltalk appeal to me more, personally.
But Adobe appears intent to make Actionscript as much a static language as possible, and one that has a fairly strict boundary between development-time and run-time. Sadly.
I don't think this can or should be chalked up to security. There are better solutions to security than to throw out run-time evaluation altogether.
Oh well. As Peter has demonstrated, reflection still works fine, so you just build your own eval() for whatever language you desire.
3 comments:
My understanding - although I've never actually tested this - is that eval() in ActionScript has always been more limited than in JavaScript. As I understand, ActionScript's eval() doesn't really provide anything more than what you can get by using subscripts to dynamically access member variables.
In ActionScript you can do this:
eval("myobject.property"+x) = 4;
but not this:
eval("1+1");
(I first read about ActionScript's eval() elsewhere, but I refer to Wikipedia: http://en.wikipedia.org/wiki/Eval#ActionScript)
Rich
Rich is correct. ActionScript's eval(name) has always been little more than shorthand for this[name] with dot expansion and searching of a few different namespaces. It has never and will never actually interpret code, ActionScript is compiled down to a very simple stack based bytecode with a VM that has no idea what ActionScript syntax looks like. ActionScript effectively has as much business eval'ing ECMAScript code as PostScript does.
If you really need to evaluate a string to a numeric result, use the externalInterface to call a javaScipt function in your HTML wrapper. Pass it the string to be evaluated. The javaScript function takes the string as a parameter, and is a one liner:
(in its own script tag)
function myEval(str)
{
return eval(str);
}
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