[Zope3-dev] Re: Merging schema & interfaces (was: "Sub interface")

[Derrick 'dman' Hudson]

On Tue, Mar 02, 2004 at 09:49:53AM -0500, Jim Fulton wrote:
| Derrick 'dman' Hudson wrote:
| >On Tue, Mar 02, 2004 at 10:10:34AM -0300, Sidnei da Silva wrote:
| >| | On Mon, 01 Mar 2004 10:05:08 -0500
| >| | Jim Fulton <jim at zope.com> wrote:
| >| | [..]
| >| | > There is a separate schema package because schema are much newer than
| >| | > interfaces. It's a packaging issue, not a technical issue.  I'm open
| >| | > to merging the schema package into the interface package at some
| >| | > point.
| >| 
| >| Now that the subject came up, I would like to ask your opinions on
| >| improving field constraints a bit, so one can have a bit more context
| >| (like the object bound to the field for example). What do you think?
| >
| >I think this is essential.
[...]

| >This does bring up the issue, though, of order of evaluation.  Perhaps
| >a field could have two constraints - the first is applied only to the
| >pending value of the field, the second has access to all the pending
| >values.  All context-independent constraints are evaluated before any
| >context-dependent ones are.  This way a field can have an independent
| >sanity check that must pass before any other fields' context-dependent
| >constraints see the value.
| 
| This road leads to madness. I know, I've been down it before. :)

:-)  Yeah, the next issue is what order to evaluate the
context-dependent constraints, and so on.

| I've come to the conclusion that it is a mistake to try to deal with
| relationships between multiple fields in individual field constraints.
| 
| To deal with constraints on multiple fields, we will add the ability to
| model interface/schema-level invariants/constraints.
[...]

This sounds like a better idea.

-D

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