On Nov 8, 2007, at 9:14 AM, Jim Fulton wrote:
 class TransactionFailedError(Exception):
"""Cannot perform an operation on a transaction that previously failed.


An attempt was made to commit a transaction, or to join a transaction, but this transaction previously raised an exception during an attempt to commit it. The transaction must be explicitly aborted, either by invoking abort() on the transaction, or begin() on its transaction
     manager.
     """

Why not subclass TransactionError?

It didn't before. Should it? There's also a DoomedTransaction exception in the interfaces package that could.

 TransactionError.__bases__ += (POSError,)
 TransactionFailedError.__bases__ += (POSError,)

Is this *really* necessary? It's obviously a bit evil. Let's explore alternatives to this:

1. Just don't do it. I'd be a bit surprised if there was code actually catching POSError.

Me too; +1. If I notice anything relying on them inheriting from POSError, I'll move POSError into the transaction module.

- I've created a zc.zodbutils package that is essentially the code that currently lives in the ZODB.utils module; I've also moved the TimeStamp.c code that currently lives in 'persistent' into it. A stub ZODB.utils module exists that just does "from zc.zodbutils import *", and in the persistent package's __init__.py, I
 do "from zc.zodbutils import TimeStamp" for backwards compatibility.

I'd rather not do this. Let's be a bit more selective here. The number of imports from ZODB are pretty limited. Many of them should move to transaction. Some of them are just test utilities that can be duplicated.

I think the biggest challenge is WeakSet. This could be broken out into a separate package, but I think it's not as general as its name implies and should probably just be moved to transaction.

OK.

And I'm thinking that the transaction distribution should be named just "transaction".

Yes, unless we decide to move the package. I think transaction is a bit presumptuous. :)

How about "zope.transaction"? There's a good deal of 3rd-party code that does "import transaction" but we could supply a module alias for this purpose. We'd just change the Z2 and Z3 appserver distributions to do "import zope.transaction as transaction" or whatever, and have the appserver distributions depend on a shim "transaction" module or module alias or whatever too so 3rd-party code would continue to work, maybe making imports using them issue a deprecation warning?

- C

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