Sounds like UUIDS or GUIDs would have been an even better identification scheme. -- Alexander Staubo http://www.mop.no/~alex/ "`Ford, you're turning into a penguin. Stop it.'" --Douglas Adams, _The Hitchhiker's Guide to the Galaxy_

-----Original Message----- From: Rob Page [mailto:rob.page@digicool.com] Sent: 22. juli 1999 15:00 To: 'Itamar S.-T.' Cc: 'zope@zope.org' Subject: RE: [Zope] Upgrading Zclasses

...

What happens if two different people create ZClasses with the same IDs?

For example: Alice creates ZClass Foo. It gets an ID of 2. Bob creates ZClass Bar. It also gets an ID of 2.

Bob imports Foo. Since its ID is already used, I assumes it gets assigned a new one, lets say 3.

Alice changes Foo, and sends Bob the new Foo. When Bob overwrites the old Foo with the new, Zope has to know the Foo's id was changed to 3 from 2. (I admit to adding the second rhyme on purpose).

:^)

If two people create ZClasses with the same ID the scenario you describe will occur. However, the default class id (in the basic tab) is a hash (MD5?) of the hostname and time. The odds of accidentally getting the same class id (unless you change the computed default) are very small.

--Rob

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