Ron Adam wrote:
A minor correction to the Block class due to re-editing.
> def __call__(self, *args):
> self.block(*args)
> self.__del__()
This should have been.
def __call__(self, *args):
try:
self.block(*args)
except Exception, self.__err__:
pass
self.__del__()
Which catches the error in the overriden "block", (I need to change that
to say "body"), method so it can be re-raised after the "final" method
is run. The "final" method can handle it if it chooses.
Thanks to Jim Jewett for noticing. It should make more sense now. :-)
In example (1.), Lock_It lost a carriage return. It should be.
class Lock_It(Get_Lock):
def block(self):
print "Do stuff while locked"
Lock_It(mylock())()
And example (3.) should be, although it may not run as is...
## 3. A template for committing or rolling back a database:
class Transactional(Block):
def start(self, db):
self.db = db
self.cursor = self.db.cursor()
def final(self):
if self.__err__:
self.db.rollback()
print "db rolled back due to err:", __err__
self.__err__ = None
else:
db.commit()
def block(self, batch):
for statement in batch:
self.cursor.execute(statement)
statement_batch = [
"insert into PEP340 values ('Guido','BDFL')",
"insert into PEP340 values ('More examples are needed')"]
db = pgdb.connect(dsn = 'localhost:pythonpeps')
Transactional(db)(statement_batch)
disconnect(db)
Another Block class could be used for connecting and disconecting.
Cheers, Ron_Adam
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