[ZPT] Re: TALESPropertySheet or using TALES as a propertydefinition

[Evan Simpson]

Ulrich Eck wrote:

> there is some info in the ZPT-Wiki about your vision a new kind of 
> PropertySheet .. do you have any examples avaliable or are this
> just thoughts.


Just thoughts, I'm afraid.

> I want to be able to define Properties in TALES.
> 
> e.g. id: "mytitle", value: "python:here.title_or_id()"

Sorry this response took so long.  Here's a sample session that may help 
(I'm CCing to ZPT in case this may help others):

 >>> from Products.PageTemplates.Expressions import getEngine
 >>> e = getEngine()
 >>> expr = e.compile('python:x+1')
 >>> c = e.getContext({'x': 1})
 >>> c.evaluate(expr)
2
 >>> c.evaluateText(expr)
'2'
 >>> c.evaluateBoolean(expr)
1
 >>> c.beginScope()
 >>> c.setLocal('x', 5)
 >>> c.evaluateText(expr)
'6'
 >>> c.endScope()
 >>> c.evaluateText(expr)
'2'
 >>> # The following is less efficient, but more direct:
 >>> c.evaluateText('string:$x!')
'2!'

The dictionary that you pass to getContext() defines builtin variables. 
  If you want to detect a return value of 'default', compare the value 
to c.getDefault().  The TALES exception is c.getTALESError().

Cheers,

Evan @ Zope