[ZODB-Dev] Proposal (version 2): cross database reference seat belt

[Christian Theune]

Hi,

On Tue, 2009-04-28 at 13:54 -0400, Jim Fulton wrote:
> Thanks again!
> 
> (Note to everyone else, Shane and I discussed this on IRC, along with  
> another alternative that I'll mention below.)
> 
> I like version 2 better than version 1.  I'd be inclined to simplify  
> and it and skip the configuration flag and simply publish an event any  
> time we see a cross-database reference when saving an object.
> 
> Here's proposed solution 3. :)
> 
> - We add a flag to disable new cross-database references unless they  
> are explicitly registered.
> - We add a connection method to register a reference:
> 
>       def registerCrossDatabaseReference(from_, to):
>             "Register a new cross-database reference from from_ to to."
> 
> - We arrange that connections can recognize old cross-database  
> references.
> 
> If someone accidentally creates a new reference and the flag is set,  
> then transaction will be aborted.
> 
> An interim step, if we're in a hurry to get 3.9 out, is to simply add  
> the flag.  This would disallow cross-database references in new  
> applications.  These applications could still support multiple  
> databases by providing application-level traversal across databases.

I think I'm reading something incorrectly: is there an emphasis on
"*new* applications"? The flag would disallow the creation of
cross-database references for a given DB -- independent of whether the
app is new or old, right? Only depending on whether the application uses
a ZODB that has the feature and has it enabled. Right?

Otherwise, I'm +1.

Christian

-- 
Christian Theune · ct at gocept.com
gocept gmbh & co. kg · forsterstraße 29 · 06112 halle (saale) · germany
http://gocept.com · tel +49 345 1229889 7 · fax +49 345 1229889 1
Zope and Plone consulting and development
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