DataError when underlying type changes

Thanks @dvarrazzo. Scoping our register_composite calls to the connection or cursor would narrow the race condition, but wouldn't eliminate it. I'm not sure we can eliminate it, though, so what would you think of raising a subclass of DataError in CompositeCaster.parse instead of DataError itself? That way our application could catch that (without swallowing other, unrelated DataErrors) and then retry register_composite or take other measures. Would this be acceptable to you?

Hello Chad,

the use case for such subclass is fairly restricted, and I think it would be more the hassle to document it than its general usefulness, not to mention that people is usually unhappy to get a new feature in rel. 2.5.2.

So my suggestion is you make your own subclass of the adapter, which should be something as easy as (untested):

class CompositeChanged(DataError):
    pass

class OurCompositeCaster(CompositeCaster):
    def parse(self, s, curs):
        try:
            return super(OurCompositeCaster, self).parse(s, curs)
        except DataError, e:
            raise CompositeChanged(str(e))

this should do everything you need.

Sounds sensible. Thanks Daniele! :-)