Question

So let’s say i have this python code:

def loopForEachFileInDirectory(self, conn):
    for filename in os.listdir(uploadedFilesDirectory):
        try:
            self.insertNewEntryForStagingFile(conn, filename)
            self.copyFilesToStagingDirectory(filename)
        except: ???

def copyFilesToStagingDirectory(self, filename):
    logging.info("copying %s to youtube_ready",filename)
    try:
        shutil.copy(uploadedFilesDirectory+filename, stagingDirectory)
        logging.info("move successful")
    except shutil.Error,e:
        logging.warn("move failed for reasons \n\t%d:%s", e.args[0],e.args[1])
        raise ???

Now, the “loopForEachFileInDirectory” method is going to have a few more methods in it – i’m doing a bit of clean coding (cheers Robert Martin) here. What i’d like is to bubble up any exceptions from the sub-methods, and if anything happens in the main loop, bail on that loop and continue.

The question is, what is the rule for bubbling up a generic exception? Do i just raise on its own? And if so, how do i generically throw an exception, and how do i catch and log the details of a generic exception?

Answer 1

what is the rule for bubbling up a generic exception? Do i just raise on its own?

Yes. The short answer is to just use raise.

And if so, how do i generically throw an exception…

The above answer the other submitter posted is correct, but it doesn’t provide much in the way of context.

Exception is the base class exception. except Exception works across all types of
Exception because all Python exceptions inherit from this class.

except statements can specify an argument which points to the the exception object.

I don’t believe that specifying it is strictly necessary in this context. In fact, it’s likely sufficient to bubble up an exception with the default:

except:
  raise

without any real need to specify an exception type or the variable e referencing the particular exception object.

..and how do i catch and log the details of a generic exception?

logging.exception is a good way to go. Try it like so:

try:
   <something that raises an error>
except Exception, e:
   logging.exception(e)