Hi Gustavo

Yeah I have thought about writing custom Predicates.

The main problem I saw with it was it appears I would have to pass in the
object to be checked at
predicate instantiation time, rather than at evaluation time.

evaluate only takes environ and credentials.
Which means I would have to somehow stuff the entity into the wsgi environ
or I would be retrieving the object
a second time inside the evaluate predicate, when I already have it. And
that would seem expensive (I am running on App Engine).

So using your example from the docs.

It would look something like.

from repoze.what.predicates import Predicate

class is_author(Predicate):
   message = 'Only %(author)s can manage post %(post_id)s'

   def __init__(self,context,**kwargs):
       self.context = context

   def evaluate(self, environ, credentials):

       if self.context.author != credentials.get('repoze.what.userid'):
           self.unmet(post_id=post_id, author=post.author_userid)

And then

# Can the user edit the post?  (must be site manager or owner)

from repoze.what.predicates import Any, has_permission
p =  Any(has_permission('site_manager'),is_author(context))


On Tue, Feb 16, 2010 at 5:41 AM, Gustavo Narea <m...@gustavonarea.net> wrote:
> Hello, Tim.
> The groups/permissions functionality is just something basic and
> optional, to help people get started, although for some smaller projects
> it may be good enough. For finer-grained control, you may want to check
> this:
> I've never really wanted to offer a similar functionality
> out-of-the-box. I've given some thought to this, and never came up with
> non-intrusive way of addressing this kind of situations. But I'm always
> open to hear alternatives.
> I hope this is what you were looking for.
>  - Gustavo.
> On 15/02/10 15:19, Tim Hoffman wrote:
>> Hi
>> I am trying to work out how I could protect a specific resource/entity
>> using repoze.what.
>> For instance I have a specific "Record", owned by a specific "User", and
>> only a user with the "Owner" permission can "Edit" the record.
>> I can't work out how you would assign "Owner" permission to the user only
>> accessing "Record".  i.e the user in question would not be owner of
>> any other record.
>> It seems the group source and permission source act on a global basis
>> and aren't context aware.  And predicates check_authorization() calls
>> only take a environ
>> and therefore you can only protect things like URL's not entities.
>> Am I trying to do something not possible/intended for repoze.what.
>> I suppose I am looking for functionality similiar to zope2
>> permissions/roles etc...
>> T
>> _______________________________________________
>> Repoze-dev mailing list
>> Repoze-dev@lists.repoze.org
>> http://lists.repoze.org/listinfo/repoze-dev
> --
> Gustavo Narea <xri://=Gustavo>.
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