[elephant-devel] Class Evolution

[Waldo Rubinstein]

Thanks. This is helpful.

- Waldo

On Dec 29, 2005, at 10:56 AM, Dan Knapp wrote:

>   Internally, Elephant stores a list of the slots in each object,  
> by their names.  So, the new slot will be unbound in the existing  
> objects - you can check using slot-bound-p.  If you delete a slot,  
> the old values for objects that had it will still be in the  
> database, but they will be harmless.  New objects will always be  
> stored according to the definition that's loaded at the time.  If  
> you want to rename a slot, you'll have to write migration code to  
> copy everything from the old slot to the new one.
>
> -- Dan Knapp
>
> On Dec 29, 2005, at 1:47 AM, Waldo Rubinstein wrote:
>
>> Is Elephant friendly with class evolution? For example, if I  
>> create a CLOS object with, say 5 fields, and store some instances  
>> in an elephant DB and then the CLOS definition of the class  
>> changes to add a sixth field. What will happen to the existing  
>> five objects when retrieved? Will new objects be stored with the  
>> new field definition?
>>
>> Thanks,
>> Waldo
>>
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>>
>
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