Honored twistedeers,
Consider the following (blocking) decorator, which runs a function in a transaction:
def _with_transaction(f): def decorated(self, *args, **kwargs): conn = self.engine.connect() txn = conn.begin()
try: result = f(self, conn, *args, **kwargs) except: txn.rollback() raise else: txn.commit() return
return decorated
Where I to translate this logic verbatim to @inlineCallbacks, I get:
def _with_transaction(f): @inlineCallbacks def decorated(self, *args, **kwargs): conn = yield self.engine.connect() txn = yield conn.begin()
try: result = yield f(self, conn, *args, **kwargs) except: yield txn.rollback() raise else: yield txn.commit() returnValue(result)
return decorated
However, there’s a bug here! In the except clause: there’s an (implicit) current exception, to be re-raised by the bare raise statement. Unfortunately, when doing yield txn.rollback(), that conveniently eats said exception.
Of course, there’s a fairly simple workaround involving catching BaseException and capturing the exception instance explicitly.
I’m wondering if this is just a leaky abstraction, or if I should report it as a bug in @inlineCallbacks?
cheers lvh