[z3-five] Attribute gives: security declaration for nonexistent method

[Tres Seaver]

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Maurits van Rees wrote:
> Hi,
> 
> In an interface I have an Attribute:
> 
>     bookinglist = Attribute("List of individual Bookings")
> 
> Now when starting Zope, I get a warning:
> 
> WARNING Init Class Products.Five.metaclass.BookingListView \
> has a security declaration for nonexistent method 'bookinglist'
> 
> Everything works as expected as far as I can see, so it does not look
> like a real problem.  But is there a way to get rid of this warning?
> 
> Ah, the warning gets throws at the end of lib/python/App/class_init.py
> as it can't find an attribute with the name 'bookinglist' in that
> class.  And that is correct as I set that in the __init__.py of the
> view class, so at Zope startup time it is not known.
> 
> So: should all Attributes of a browser view be set in the class
> definition outside of the __init__()?  Well, all Attributes that are
> indicated by the Interface at least.  Correct?
> 
> It gets rid of the warning anyway and looks like good practice.

It also makes it possible to verify the conformance of the class to the
interface::

   >>> from zope.interface.verify import verifyClass
   >>> from mypackage.interfaces import IFoo
   >>> from mypackage.foo import Foo
   >>> verifyClass(IFoo, Foo)  # doesn't raise

An added benefit is that setting defaults at the class level seems more
readable than setting them in the __init__,


Tres.
- --
===================================================================
Tres Seaver          +1 540-429-0999          tseaver at palladion.com
Palladion Software   "Excellence by Design"    http://palladion.com
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