[z3-five] Wrapping Z2 interfaces (maybe, "bride of Frankenzope"?)

[Martijn Faassen]

Tres Seaver wrote:
> For existing Zope2 applications which already declare and use Zope2 
> interfaces, it seems natural to re-use those specifications.  I have a 
> utility module (with a handful of tests) which exports 
> 'fromZ2Interface', a function which introspects a Zope2 interface object 
> and synthesizes an "equivalent" Zope 3 interface.

Sounds like a useful thing to me. Interesting!

> I am currently using it in a scratch product, CMFonFive, 

Very interesting name, that. :)

> to populate the 
> 'interfaces' module, e.g.:
>  
>   from utilities import fromZ2Interface
> 
>   from Products.CMFCore.interfaces.CachingPolicyManager \
>       import CachingPolicyManager as _IZ2_CachingPolicyManager
> 
>   ICachingPolicyManager = fromZ2Interface(_IZ2_CachingPolicyManager)
> 
>   del _IZ2_CachingPolicyManager
> 
> 
> The amount of noisy boilerplate in that module is painful:  I did take 
> the opportunity to rename CMF interfaces, but that is the only real 
> "value" the module adds.  I am pondering a ZCML directive which would
> remove the need for the boilerplate;  something like:
> 
>   <five:bolt-on
> 
> source="Products.CMFCore.interfaces.CachingPolicyManager.CachingPolicyManager" 
> 
>     target=".interfaces.ICachingPolicyManager"
>     />
> 
> Would the utility be useful in Five?  The directive?

Yes, sounds like a good idea! Just to be clear, this would be a utility 
as in 'utility module', not as in "Zope 3 utility" right? A module is 
definitely a bit easier to integrate. Z3 utilities I think work (at 
least global ones), but we haven't done a lot of testing.

I'd suggest another name for the directive though. Hm, perhaps 
five:convert-interface

<five:convert-interface
 
zope2="Products.CMFCore.interfaces.CachingPolicyManager.CachingPolicyManager"
zope3=".interfaces.ICachingPolicyManager"
/>

I'm not sure about the zope2 and zope3 attributes, though that would 
make it fairly clear what we're dealing with.

Or perhaps we could call it five:bride :).

Regards,

Martijn