#!/usr/bin/env python
     # encoding: utf-8
     
     import sys
     
     def trace_exceptions(frame, event, arg):
         if event != 'exception':
             return
         co = frame.f_code
         func_name = co.co_name
         line_no = frame.f_lineno
         filename = co.co_filename
         exc_type, exc_value, exc_traceback = arg
         print 'Tracing exception: %s "%s" on line %s of %s' % \
             (exc_type.__name__, exc_value, line_no, func_name)
     
     def trace_calls(frame, event, arg):
         if event != 'call':
             return
         co = frame.f_code
         func_name = co.co_name
         if func_name in TRACE_INTO:
             return trace_exceptions
     
     def c():
         raise RuntimeError('generating exception in c()')
     
     def b():
         c()
         print 'Leaving b()'
     
     def a():
         b()
         print 'Leaving a()'
         
     TRACE_INTO = ['a', 'b', 'c']
     
     sys.settrace(trace_calls)
     try:
         a()
     except Exception, e:
         print 'Exception handler:', e