How to display last traceback

[alexpul]

I'm looking for a way to display the latest traceback. I have a wipy that runs a script for a long time so I disconnect it from the REPL, which means that when an error occurs I can't see the line number where it occurred. Definitely makes debugging difficult! I know that sys.exc_info() gives the exception that occurred but I also need to know where it occurred. Ideally, I'd like to just display the last traceback in the REPL when I reconnect to the device and to avoid try/catch statements because the code is long. Any ideas?

[alexpul]

@crumble Not a bad work around! Thanks for your help.

[crumble]

You can write the output of print_exception() into a file

import sys
try:
    raise ValueError('Hellas ', 1, 2, 3)
except Exception as e:
    f2 = open('/sd/exceptions.txt', 'a')
    f2.write('\nException at: ' + str(rtc.now()))
    sys.print_exception(e, f2)
    f2.close()

reading it from REPL is not nice, but you can write a method for the UX

f2 = open('/sd/exceptions.txt', 'a')
e = f2.read()
print(e)
f2.close()

The result will look like:

Exception at: (2019, 2, 19, 19, 46, 19, 620384, None)Traceback (most recent call last):
  File "main.py", line 101, in <module>
ValueError: ('Hellas ', 1, 2, 3)

Exception at: (2019, 2, 19, 19, 54, 55, 351626, None)Traceback (most recent call last):
  File "main.py", line 101, in <module>
ValueError: ('Hellas ', 1, 2, 3)

I found an implementation of pickle, but it was not able to load string. So you can use only the output.

[alexpul]

@crumble Thanks for the quick reply. Unfortunately the try/except method doesn't work after the error has occurred. If the device isn't connected to the REPL when the error occurs you cannot retrieve the traceback. I know you can save the exception to a file but I'd like to just print it in the REPL but after the error occurs.

[crumble]

import sys

[...]

except Exception as e:               
    sys.print_exception(e)