[Zope-CMF] [dev] using newstyle content factories - a proposal

[yuppie]

Hi!


In Zope there are two ways to register content classes and factories:

Oldstyle::

     class Foo:
         meta_type = 'Foo Type'

     def manage_addFoo(folder, id):
         ob = Foo(id)
         folder._setObject(id, ob)

     context.registerClass(
         Foo,
         constructors=('manage_addFoo',),
         permission=AddFoo,
         )

Newstyle::

     class Foo:
         # the meta_type attribute is added by registerClass

     FooFactory = Factory(Foo)

     <five:registerClass
         class=".Foo"
         meta_type="Foo Type"
         permission="fooproduct.AddFoo"
         />

     <factory
         component=".FooFactory"
         id="fooproduct.foo"
         />


Oldstyle factories are used this way::

     dispatcher = folder.manage_addProduct['FooProduct']
     dispatcher.manage_addFoo('foo')

And newstyle factories like this::

     factory = getUtility(IFactory, 'fooproduct.foo')
     ob = factory(id)
     folder._setObject(id, obj)

FactoryTypeInformation currently just supports oldstyle factories.


Proposal
========

If the 'product' property of a type info instance is empty the 'factory' 
property is interpreted as a newstyle factory ID.


Risks
=====

Newstyle factories are placeless, they know nothing about the container 
and can't add the objects themselves to the container. There are many 
complex factories out there that can't be easily replaced by newstyle 
factories. So we can't deprecate the old way - at least for now.


Any feedback is welcome. If there are no objections I'll check in the 
proposed change on the trunk.


Cheers,

	Yuppie