[Zope-dev] Specialists and __bobo_traverse__

[Steve Alexander]

Chris Withers wrote:

> Steve Alexander wrote:
> 
>> If ob is not found, you'll get an error raised. You need to have some
>> sort of marker for the default value.
> 
> 
> Is there any reason why no-one uses None as a marker?

Yes. An attribute that exists can have the value None.

class foo:
   bar=None

You need to distinguish between this case, and the case where the 
attribute does not exist.

--
Steve Alexander
Software Engineer
Cat-Box limited
http://www.cat-box.net