Christian Theune wrote:
I didn't find anything in the documentation or google on this:
I want to define an interface like:
class IMySchema(zope.interface.Interface):
pass
Later, I want to use ore.alchemist which currently is able to take a
SQLAlchemy table description and turn it into a new interface/schema.
I want to extend this code so that I can pass it an existing interface
to modify it (update) with the schema definition.
I need this so that the interface is:
a) present in the code when reading it
b) available for ZCML configuration (it's a problem for us right now
because the database/SQLAlchemy stuff is setup up a little bit later
after executing a couple of ZCML actions)
While looking into it, we found that interfaces do not offer a public
way to modify the attributes they have, and modifying the internal data
structures would be both evil and cumbersome.
Any hints?
I would recommend creating a *sub*interface of the IMySchema on-the-fly.
That way registrations for IMySchema will also apply to the
subinterface, but you won't have to worry about mutating IMySchema.
This is easily possible:
IMySchemaSub = InterfaceClass('IMySchemaSub', (IMySchema,),
{'field1': TextLine(), ...},
__doc__='...', __module__='...')
Note that if you attach the interface on persistent objects using
alsoProvides/directlyProvides, you need to put the interface in a module
so the ZODB can continue to import it when waking up these objects. Put
it in the same module that you gave the InterfaceClass constructor
(__module__).
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