From the output presented on the previous page, we can conclude that we have to deal with a traceback type object.
To achieve this, we could use the format_tb() method delivered by the built-in traceback module to get a list of strings describing the traceback.
We could use the print_tb() method, also delivered by the traceback module, to print strings directly to the standard output.
The corresponding output reveals the sequence of exceptions and proves that the execution was not interrupted by the exceptions because we see the final wording Final check is over.
Final check procedure
The captain's name is John
The pilot's name is Mary
The mechanic's name is Mike
<traceback object at 0x00D373A0>
<class 'traceback'>
Traceback details
File "exceptions#090.py", line 22, in <module>
personnel_check()
File "exceptions#090.py", line 14, in personnel_check
raise RocketNotReadyError('Crew is incomplete') from e
Final check is over
output
Now your log book could be filled with lots of details about your rocket launch for later investigation.
In real life development projects, you may make use of logged tracebacks after comprehensive test sessions to gather statistics or even automate bug reporting processes.
For more information about chained exceptions and traceback attributes, look at the PEP 3134 document.
Code
import tracebackclass RocketNotReadyError(Exception):
pass
def personnel_check():
try:
print("\tThe captain's name is", crew[0])
print("\tThe pilot's name is", crew[1])
print("\tThe mechanic's name is", crew[2])
print("\tThe navigator's name is", crew[3])
except IndexError as e:
raise RocketNotReadyError('Crew is incomplete') from e
crew = ['John', 'Mary', 'Mike']
print('Final check procedure')
try:
personnel_check()
except RocketNotReadyError as f:
print(f.__traceback__)
print(type(f.__traceback__))
print('\nTraceback details')
details = traceback.format_tb(f.__traceback__)
print("\n".join(details))
print('Final check is over')