Lennart Regebro wrote:
On 10/29/05, Chris Spencer <[EMAIL PROTECTED]> wrote:
Would it be possible to support some system of class versioning in ZODB,
to aid to handling modifications to source code? For instance, suppose
each class definition has a __version__ attribute. Upon serialization,
this version is saved for each instance. Then, if the class is updated,
signified by incrementing the class's __version__, ZODB could take
action, for example, by executing an optional __upgrade_to_x(self) in
the new class definition.
I don't see what benefits that would bring. It's quite easy to
implement something like this on an application level. Also this
doesn't allow for upgrades where you need to replace the object, which
are not uncommon, so it's still not a complete solution.
Agreed. For an example of such an application-level solution,
see:
http://svn.zope.org/Zope3/trunk/src/zope/app/generations/README.txt?view=markup
Note that even though this package is in zope.app, the solution is quite
general and should be usable outside of Zope. (This package really should be
lifted up a level.)
Jim
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