[Zope3-dev] Re: Providing flexible adapters

[Shane Hathaway]

Phillip J. Eby wrote:
> At 10:40 AM 2/26/02 -0500, Shane Hathaway wrote:
> 
>> Zope 3's answer is to make a reference generation utility.  It would 
>> be a very, very simple utility that might just look up an adapter.  If 
>> we later decide that the adapter registry is sufficient, we can just 
>> leave it that way.  If we instead decide that generating a reference 
>> depends on not just the interfaces of the object, but also the 
>> interfaces of the object's context (or something else), we can make a 
>> new service.
> 
> Interesting.  Are utilities placeful?

Yes.  So are adapters, utilities, and services.

> I'm not sure that putting the utility in front of the adapter gives any 
> advantage for this situation, however.  One could always register an 
> adapter that looked up the utility, right?  So if we expect the normal 
> case to be just an adapter, it seems more straightforward to use the 
> adapter, reducing the number of layers of delegation for the common case.

I agree, but I'm not sure that the normal case is an adapter.  And if it 
is, but we don't provide a way to change how references are created, how 
will people implement the special cases?

> Then maybe there should be an IReferenceable adapter that adapts 
> anything, by looking up a placeful utility.  :)  Then we get two for the 
> price of one, so to speak.  Ain't ZCA grand?  :)

I'm trying to reuse concepts from the Python language.  Every object in 
Python is implicitly "referenceable".  I do not believe there is a need 
to further abstract the concept.

Shane