[Zope3-dev] Re: object arg overloaded in IAdapterService.getAdapter

[Jim Fulton]

I agree that there should be an optional place to look up the
adapter as an alternate to the place of the adapted object.

In fact, I remember deciding this a long time ago although it 
might have been for views. I even wrote it down. Now, where
was that .... ;)

Please feel free to add this or to add a task to the collector.

Jim

Steve Alexander wrote:
> 
> In the IAdapterService interface, the object argument is overloaded with
> two meanings.
> 
>      def getAdapter(object, interface, default=None):
>          """Look up an adapter that provides an interface for an object
> 
>          The object also provides a place to look for placeful adapters.
> 
>          A Zope.ComponentArchitecture.ComponentLookupError will be
>          raised if the component can't be found.
>          """
> 
> I would like to have the meanings separated out into:
> 
>    * the place to look for placeful adapters
> 
>    * the interfaces to adapt from
> 
> Here's why:
> 
> Take the example of an IContact object that I want to get city/state
> information for.
> 
> Let's say there are two placeful adapter-makers for this:
> 
>    1: a free service that has low quality information
> 
>    2: a paid-for service that is backed by a large up-to-date database
> 
> The service that I get to use should depend on the context of the caller
> of getAdapter, not on the context of the IContact object I'm adapting.
> 
> To do this, we need to have the option of not overloading the "object"
> argument in getAdapter, and instead have two arguments: placeful_context
> and object_to_adapt. (rename as needed.)
> 
> Until about 10 minutes ago, I had thought that adapters were placeful in
> the caller's context. Of course, I hadn't really thought about it...
> that's how Zope 2's ubiquitous acquisition can poison one's mind ;-)
> 
> --
> Steve Alexander

--
Jim Fulton           mailto:jim@zope.com       Python Powered!        
CTO                  (888) 344-4332            http://www.python.org  
Zope Corporation     http://www.zope.com       http://www.zope.org