[Laszlo-user] create a class by name

P T Withington ptw at pobox.com
Fri Oct 12 11:46:03 PDT 2007


eval is very limited in the swf runtime.  It can only evaluate var  
and member expressions.

Are you just trying to create a particular class, or do you need the  
class to be variable, or do you need the name of the class to be a  
variable?  E.g., you can just say:

   new TestClass();

Or:

   var theclass = TestClass;
   ...
   new theclass();

Or:

   var theclassname = "TextClass";
   ...
   new global[theclassname]();

All of these work.  Your mechanism is what is used to evaluate a  
general expression, and is required because of the limited nature of  
eval in the swf runtime.  It is basically calling back to the server,  
having the server compile the expression, and then loading the  
compiled code to evaluate it.

In the DHTML runtime, eval is fully-featured, but remember it is a  
security hole.  If you allow arbitrary user input to be evalled, you  
really have no control...


On 2007-10-12, at 14:12 EDT, Ruben Reusser wrote:

> Hi:
>
> Is it possible to create a class by name in OpenLaszlo? I tried:
>
> eval("new TestClass()");
>
> but this does not work. The only solution I could find was the  
> following:
>
> loader.request( { lz_load : false,lzt : "eval",proxied: true,url:  
> "__debugger.lzx",lz_script : "#file interactive-eval-0\nnew  
> TestClass()"} );
>
> not my favorite approach.
>
> Ruben
>



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