[Zope-dev] Callable baseclass for ZClasses

[Stefan H. Holek]

Taking ideas from the Renderable product, the ZCallable baseclass
(PTK) and the __call__ thread on this very list, I created a Callable
baseclass intended as a mixin for ZClasses.

class Callable:

  def render( self, client=None, REQUEST={}, RESPONSE=None, **kw ):
    '''Calls index_html, if it exists, to render this object.
    '''
    self.isDocTemp = 1			# pass me the namespace, please                          
    local = getattr( self, 'aq_base', self ) 
    if hasattr( local, 'index_html' ):
      method = self.index_html
      args = (self, REQUEST, RESPONSE)  # substitute self for client
      return apply( method, args, kw )
    else:
      raise AttributeError, 'index_html'

  __call__ = render

I went on to make a ZClass derived from Folder and Callable to effectively
create a CallableFolder. Man, was I proud ;). This worked fine for me
until I had to put some security on my CallableFolders. Removing 'View'
for Anonymous keeps me from accessing a CallableFolder directly but it can
still be used as a subtemplate (dtml-var x) from another DTML Document or
Method. Bummer! Doing some tests I discovered that plain DTML Documents
show the same behaviour (!), though DTML Methods throw 'Unauthorized' as
expected.

Now I am confused and herewith ask the pros to kindly have a look at
what I did.

*) Does my baseclass do what I expect it to at all? (or only by chance ;)
*) Is there a known issue with DTML Documents used as subtemplates or is
   their behaviour correct?
*) Do I have to take measures in my baseclass to properly access/pass
   security contexts? 
*) If yes, how would I do it?
*) Or is there even prior art on such a baseclass or reasons why this just
   cannot possibly work?

If you are interested, you can get the CallableFolder product in its
current state from ftp://epy.co.at/pub/zope/

I am running Zope 2.2.2 with both Hotfixes and the __call__ fix.

Thanks,
Stefan

--
Things work better when plugged in