Catching warnings pre-python 2.6

Question

In Python 2.6 it is possible to suppress warnings from the warnings module by using

with warnings.catch_warnings():
    warnings.simplefilter("ignore")
    fxn()

Versions of Python before 2.6 don't support with however, so I'm wondering if there alternatives to the above that would work with pre-2.6 versions?

Answer 1

This is similar:

# Save the existing list of warning filters before we modify it using simplefilter().
# Note: the '[:]' causes a copy of the list to be created. Without it, original_filter
# would alias the one and only 'real' list and then we'd have nothing to restore.
original_filters = warnings.filters[:]

# Ignore warnings.
warnings.simplefilter("ignore")

try:
    # Execute the code that presumably causes the warnings.
    fxn()

finally:
    # Restore the list of warning filters.
    warnings.filters = original_filters

Edit: Without the try/finally, the original warning filters would not be restored if fxn() threw an exception. See PEP 343 for more discussion on how the with statement serves to replace try/finally when used like this.

Answer 2

Depending on what the minimum version you need to support using Python 2.5's

from __future__ import with_statement

might be an option, else you'll probably need to fallback to what Jon suggested.