[Zope] <dtml-var x missing> doesn't work?

[Tino Wildenhain]

hi again, 

Chris Withers wrote:
> 
> Hi,
> 
> I'm doing a back link to go on a page (yes, I know browsers have back buttons, but some people don't
> like to use them ;-) which is easy enough:
> 
> <A href="<dtml-var "REQUEST.environ['HTTP_REFERER']">">Back</A>
> 
> except that if there is no referer, you get a key error. So I thought I'd try the following:
> 
> <A href="<dtml-var "REQUEST.environ['HTTP_REFERER']" missing='/'>">Back</A>
> 
> But I still get a key error. I thought the 'missing' attribute was supposed to catch that?

Btw. this works:

<dtml-with REQUEST>
  <dtml-with environ>
    <dtml-var HTTP_REFERER missing>
  </dtml-with>
</dtml-with>

or 

<dtml-with "REQUEST.environ">
    <dtml-var HTTP_REFERER missing>
</dtml-with>

if you want :-)

Regards,

Tino Wildenhain