best way to run python generator cleanup code

Question

I\'m trying to write a generator function that gets rows out of a database and returns them one at a time. However, I\'m not sure if the cleanup code marked ** below execute

Answer 1

Your version will run dbc.close() as soon as d is None, but not if an exception gets raised. You need a finally clause. This version is guaranteed to run dbc.close() even if an exception gets raised:

try:   
    myDB = MySQLdb.connect(host=..., port=..., user=..., passwd=..., db=...)   
    dbc = myDB.cursor()
    dbc.execute(stmt)
    d = "asdf"
    while d is not None:
        d = dbc.fetchone() #can also use fetchmany() to be more efficient
        yield d
except MySQLdb.Error, msg:
    print("MYSQL ERROR!")
    print msg
finally:
    dbc.close()