Evaluating an XML expression within from within an XML node

Question

I would like to pass in an E4X expression from a node and
evaluate that expression.
For example, let's say the XML looks like this:
quote:
<section id="a">
<item id="1">
<value>3.1</value>
</item>
<item id="2">
<value>2.2</value>
</item>
<item id="3">
<value
calculated="true">{section.(@id=="a").item.(@id=="1").value +
section.(@id=="a").item.(@id=="1").value}</value>
</item>
</section>
I would then like to evaluate this from within Flex,
displaying each of the values from the three items and evaluating
the expression that lies in the third item.
Note: this doesn't work... (but it's the idea... that is, to
retrieve the expression from the XML and evaluate it)...
quote:
<mx:Script>
<![CDATA[
[Bindable]
public var xmlHUD:XML;
]]>
</mx:Script>
<mx:Label
text="{myXML.section.item.(@id=='3').value}"/>
If successful, the label would then display the result from
the express in item 3, which would be 5.3 (the result of 3.1 +
2.2).
Any ideas?
David

Answer 1

Your prayer is answered! :)
Check out the DAS.eval() Library; it is designed just for
this purpose. You can pass in a string of any AS3 expression
(including E4X) and even algorithms and get a value back. Check it
out at
Adobe | Communities | Exchange | Flex | Libraries
or simply go to
http://www.flexisco.com/daseval/
Cheers!
- Ann