python - How to debug a script using the module logging -

i have script using several imported submodules of mine, each of them using module logging. in 1 of them wrote bad code line, can figure out is. indeed, synthax typical logging output argument var is:

logging.info("my var=%s", var) 

if number of arguments not correspond number of %s in string, there error message logging follows :

traceback (most recent call last): file "/usr/lib/python2.6/logging/__init__.py", line 776, in emit   msg = self.format(record) file "/usr/lib/python2.6/logging/__init__.py", line 654, in format   return fmt.format(record) file "/usr/lib/python2.6/logging/__init__.py", line 436, in format   record.message = record.getmessage() file "/usr/lib/python2.6/logging/__init__.py", line 306, in getmessage   msg = msg % self.args valueerror: incomplete format 

the problem error message generic: not show name of module probleme appear, nor code line, nor arguments... makes impossible me find out wrote bad call logging.info()

q&d braindead solution : edit /usr/lib/python2.6/logging/init.py , wrap line 776 in try/except clause:

try:     msg = self.format(record) except valueerror:     import pdb; pdb.set_trace() 

then re-run code shell , whatever needed re-raise exception. you'll sent in step debugger, can inspect whole call stack.

once problem solved, rollback edits. , contribute patch logging module emits more useful error message...

oh , btw : automated tests way catch kind of errors possible, when remember part of code touched.