Generic Exception Handling in Python the "Right Way"

python exception readability
Sufian picture Sufian · Sep 24, 2008 · Viewed 53.1k times · Source

Sometimes I find myself in the situation where I want to execute several sequential commands like such:

try:
    foo(a, b)
except Exception, e:
    baz(e)
try:
    bar(c, d)
except Exception, e:
    baz(e)
...

This same pattern occurs when exceptions simply need to be ignored.

This feels redundant and the excessive syntax causes it to be surprisingly difficult to follow when reading code.

In C, I would have solved this type of problem easily with a macro, but unfortunately, this cannot be done in straight python.

Question: How can I best reduce the code footprint and increase code readability when coming across this pattern?

Answer

Ryan picture Ryan · Sep 24, 2008

You could use the with statement if you have python 2.5 or above:

from __future__ import with_statement
import contextlib

@contextlib.contextmanager
def handler():
    try:
        yield
    except Exception, e:
        baz(e)

Your example now becomes:

with handler():
    foo(a, b)
with handler():
    bar(c, d)

Related questions

How can I safely create a nested directory?

What is the most elegant way to check if the directory a file is going to be written to exists, and if not, create the directory using Python? Here is what I tried: import os file_path = "/my/directory/filename.…

Read More
Manually raising (throwing) an exception in Python

How can I raise an exception in Python so that it can later be caught via an except block?

Read More
How do I check if a variable exists?

I want to check if a variable exists. Now I'm doing something like this: try: myVar except NameError: # Do something. Are there other ways without exceptions?

Read More