#!/usr/bin/python<\/span><\/div>#<\/span><\/div># This code sample shows (what I hope to be) the right way to reraise an exception in the<\/span><\/div># situation where you have to perform some cleanup before reraising.<\/span><\/div>#<\/span><\/div> <\/div>
cleaned_up<\/span> =<\/span> False<\/span><\/div> <\/div>
def<\/span> raiser<\/span>():<\/span><\/div> raise<\/span> RuntimeError<\/span>(<\/span>"this should be reported at line 10"<\/span>)<\/span><\/div> <\/div>
def<\/span> cleanup_raises<\/span>():<\/span><\/div> global<\/span> cleaned_up<\/span><\/div> cleaned_up<\/span> =<\/span> True<\/span><\/div> raise<\/span> RuntimeError<\/span>(<\/span>"you should not see this!"<\/span>)<\/span><\/div> <\/div>
def<\/span> reraiser1<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> raiser<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>,<\/span> e<\/span>:<\/span><\/div> try<\/span>:<\/span><\/div> cleanup_raises<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>:<\/span><\/div> pass<\/span><\/div> # Wrong: stack trace reports this as the original scene of the<\/span><\/div> # crime. Location information should say line 10 but it doesn't<\/span><\/div> raise<\/span> e<\/span><\/div> <\/div>
def<\/span> reraiser2<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> raiser<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>,<\/span> e<\/span>:<\/span><\/div> try<\/span>:<\/span><\/div> cleanup_raises<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>:<\/span><\/div> pass<\/span><\/div> # Wrong: stack trace reports cleanup_raises as the culprit. We<\/span><\/div> # want to know about raiser.<\/span><\/div> raise<\/span><\/div> <\/div>
def<\/span> reraiser3<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> raiser<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>,<\/span> e<\/span>:<\/span><\/div> def<\/span> cleanup<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> cleanup_raises<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>:<\/span><\/div> pass<\/span><\/div> cleanup<\/span>()<\/span><\/div> # Right: Need to make sure that exceptions from cleanup_raises<\/span><\/div> # are handled in a separate scope. This reports the original<\/span><\/div> # exception location of raiser at line 10.<\/span><\/div> raise<\/span><\/div> <\/div>
def<\/span> reraiser4<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> raiser<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>,<\/span> e<\/span>:<\/span><\/div> (<\/span>_<\/span>,<\/span> _<\/span>,<\/span> traceback<\/span>)<\/span> =<\/span> sys<\/span>.<\/span>exc_info<\/span>()<\/span><\/div> <\/div>
try<\/span>:<\/span><\/div> cleanup_raises<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>:<\/span><\/div> pass<\/span><\/div> # Right: Raise exception but provide original traceback<\/span><\/div> # info. (Note: must call sys.exc_info() before calling any<\/span><\/div> # other possible raiser.) This also reports raiser at line 10.<\/span><\/div> raise<\/span> e<\/span>,<\/span> None<\/span>,<\/span> traceback<\/span><\/div> <\/div>
def<\/span> reraiser5<\/span>():<\/span><\/div> try<\/span>:<\/span><\/div> raiser<\/span>()<\/span><\/div> finally<\/span>:<\/span><\/div> try<\/span>:<\/span><\/div> cleanup_raises<\/span>()<\/span><\/div> except<\/span> RuntimeError<\/span>:<\/span><\/div> pass<\/span><\/div> # Right: Don't even catch the original exception -- just clean<\/span><\/div> # up on the way out.<\/span><\/div> assert<\/span>(<\/span>cleaned_up<\/span>