[Zope] Upgrading Zclasses

Alexander Staubo alex@mop.no
Thu, 22 Jul 1999 15:10:49 +0200


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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