[Zope] Getting permission information in Python (hasRole/getRoles ?)

[Emmanuel Viennet]

  In a method of a (python) product, I need to select the
objects (eg in a Folder) for which a visitor (REQUEST.AUTHENTICATED_USER)
has a given permission (eg 'Access contents information').

I tried the following scheme:

  obj = the_item_to_be_tested
  if REQUEST.AUTHENTICATED_USER.hasRole( obj, ['Access contents 
information'])):
       # add obj to result list

But hasRole() always returns None...


I then tried to use the method getRoles().
The documentation (in Products/OFSP/help/AuthenticatedUser.py) says:

     def getRoles(object):
         """
         Returns a list of the roles the user has on the given object
         (in the current context?)

         Permission -- Always available

         """

but when I try: REQUEST.AUTHENTICATED_USER.getRoles(obj)
I get a TypeError.
Strangely, I observed that without arguments,
    REQUEST.AUTHENTICATED_USER.getRoles()
returns:
    ('Anonymous',)
(for a request from 'Anoymous User').


So I need help from a Zope guru !

Emmanuel