[Zope] dynamic sort=

[D. Rick Anderson]

Is there a way to do a dynamic sort= on a dtml-in on a list of dictionaries?

like:

<dtml-call "REQUEST.set('sortby', 'firstname')">

<dtml-in "queryname_py" mapped sort=_['sortby']>
etc...

I've tried _['sortby'], _[sortby], "_['sortby']", and "_[sortby]" and I 
always get an error. Is there an easy way to do this?

Thanks,

Rick