[Zope-dev] make zope.component.registry.Components inherit from dict?

[Matthew Wilkes]

On 2009-11-24, at 0521, Chris McDonough wrote:

> I don't think I understand.  Could you provide an example?

Sure!

I think this is the same thing that Martin suggested, but here's some  
code which should make it clearer.

First, we create an object that we want to be accessible from this  
lookup:

class Root(dict):
     pass

Then, we register that as a utility in the global site manager

manager = zope.component.getGlobalSiteManager()
manager.registerUtility(Root(),
			zope.interface.Interface,
			name="root")

This can then be found with:

manager.getUtility(zope.interface.Interface, name="root")

As you can see, the special interface code has disappeared, leaving  
things only keyed on a string, the utility name.

We can then set up an adapter, something like this:

from zope.interface import Interface, implements
from zope.component import adapts
from zope.component.interfaces import IComponentRegistry

class IDictInterface(Interface):

     def __getitem__(key):
         pass

     def __setitem__(key, value):
         pass
	
     def __delitem__(key):
         pass

class DictInterface(object):

     implements(IDictInterface)
     adapts(IComponentRegistry)

     def __init__(self, manager):
         self.manager = manager

     def __getitem__(self, key):
         return self.manager.getUtility(Interface, name=key)

     def __setitem__(self, key, value):
         self.manager.registerUtility(value,
			Interface,
			name=key)
	
     def __delitem__(self, key):
         self.manager.unregisterUtility(provided=Interface, name=key)

manager.registerAdapter(DictInterface)

(N.B: rough sample code)

Once you have one of these objects instantiated your example code will  
work fine:

 >>> def root_factory(environ):
...      return {}
...
 >>> reg=IDictInterface(zope.component.getGlobalSiteManager())
 >>> reg['root_factory'] = root_factory
 >>> print reg['root_factory']
<function root_factory at 0x100628e60>
 >>> print zope.component.getUtility(zope.interface.Interface,  
name="root_factory")
<function root_factory at 0x100628e60>


Matt