[Zope3-dev] zope.schema: defaults for non-immutables... questions

Shaun Cutts shaun at cuttshome.net
Mon Feb 6 11:53:22 EST 2006

I'll keep getting Jim's agreement or putting up a proposal in mind.

As I start to think of how to extend it, I have some general question
about zope.schema. I should note that I am not currently a zope user
proper (though I will be soon), but was referred to the zope.interface
package via twisted. When I looked at it, and the zope3 book, I
immediately thought that type checking of attributes could be useful,
and so started using zope.schema. 

I've thought of several things I'd like to see in it.... The biggest
would obviously be (optional) type checking of method calls, together
with a more robust Method definition. Also it would be nice to have
something like "delegateImplementation( iface, cvar )" and
"delegateProvision( iface, ivar)" to delegate the fulfillment of an
interface to a class variable or an instance variable.

But my overall question is: since zope.schema is generally useful for
components, why is it separate from zope.interface? I can think of two
answers: one, pragmatically, zope3 wants a stable zope.interface so the
rest of the system can come up to speed. Thus we can think of schema as
sort of like the __future__ version of zope.interface. Second, as schema
came from abstracting away zope-like features from gui support, it is
meant as "proto-gui-support".

I would argue that, though it does support some features that would be
useful for a gui, it is more generally applicable to component-based

(I have been using it for-- among other things-- some souped-up database
Rows, which support transparently some postgress-specific features. The
extra introspection capabilities in zope.schema have been useful.)

But maybe Jim resists changes because he has a more specific role in
mind for zope.schema, and the development of zope.interface?

- Shaun

-----Original Message-----
From: Stephan Richter [mailto:srichter at cosmos.phy.tufts.edu] 
Sent: Sunday, February 05, 2006 4:40 PM
To: zope3-dev at zope.org
Cc: Gary Poster; Shaun Cutts
Subject: Re: [Zope3-dev] zope.schema: defaults for non-immutables...

On Sunday 05 February 2006 14:42, Gary Poster wrote:
> ...as I said, Jim disagreed with this sort of change the last time it
> was brought up.

Okay, I did not know that.

> This needs to have a proposal, or at least needs to   
> have Jim weigh in on it, IMO.

Yeah, I forgot about a proposal.

Stephan Richter
CBU Physics & Chemistry (B.S.) / Tufts Physics (Ph.D. student)
Web2k - Web Software Design, Development and Training

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