On Wednesday, June 27, 2012 1:59:38 PM UTC+2, Michael Bayer wrote:
>
>
> All of this points towards not needing to recreate the entirety of 
> mappings.   Really if you just need subclassing where the subclasses can be 
> thrown away, the patch + usage in www.sqlalchemy.org/trac/ticket/2526achieves 
> this.   in fact, even without the patch, if you had a subclass of 
> a mapped class and wanted to discard it, you could say:
>
> MyBaseClass.__mapper__._inheriting_mappers.remove(MySubClass.__mapper__)
> del MyBaseClass.__mapper__.polymorphic_map["mysubclass"]
> MyBaseClass.__mapper__._expire_memoizations()
>
> it's that _expire_memoizations() part that is difficult to make automatic, 
> as it refers to an array of attributes on the mapper() object that are 
> lazily evaluated and then memoized.   If you aren't using polymorphic 
> loading for these mappers, then even the above steps might not even be 
> needed - the additional records in these collections might just be 
> ignorable and would only be present while tests are running, not while the 
> actual app runs.
>
>
Ok, I understand why you favoured that solution. We have implemented what 
you said above and it works fine. Will keep an eye on #2526 to see what you 
decide about that...

Thank you
-i

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