implement tb_lineno of Traceback

[corona10]

I implements tb_lineno but I don't know this is right implementatation.
I know tb_linno should assigend by frame's f_lineno but this implementation looks different.
I check it print right tb_lineno on below code after this patch...

import sys, traceback

def lumberjack():
    bright_side_of_death()

def bright_side_of_death():
    return tuple()[0]

try:
    lumberjack()
except IndexError:
    exc_type, exc_value, exc_traceback = sys.exc_info()
    print "*** print_tb:"
    traceback.print_tb(exc_traceback, limit=1, file=sys.stdout)
    print "*** print_exception:"
    traceback.print_exception(exc_type, exc_value, exc_traceback,
                              limit=2, file=sys.stdout)
    print "*** print_exc:"
    traceback.print_exc()
    print "*** format_exc, first and last line:"
    formatted_lines = traceback.format_exc().splitlines()
    print formatted_lines[0]
    print formatted_lines[-1]
    print "*** format_exception:"
    print repr(traceback.format_exception(exc_type, exc_value,
                                          exc_traceback))
    print "*** extract_tb:"
    print repr(traceback.extract_tb(exc_traceback))
    print "*** format_tb:"
    print repr(traceback.format_tb(exc_traceback))
    print "*** tb_lineno:", exc_traceback.tb_lineno

[undingen]

Your patch looks good but I would prefer if you would add a test.
#1031 implements the same attribute + some additional stuff but because it may take some more time until this PR lands I'm fine with merging this one in between and rebasing mine.
But I definitely recommending to not but more effort into the traceback and frame object until #1031 landed. (I think after #1031 is merged we can even easily switch to the cpython traceback implementation)

[corona10]

@undingen Thanks, I added test. But I don't know it will be good or not to be merged mine if you 're already make patch for this. 😄

[kmod]

You could probably do offsetof(BoxedTraceback, line) + offsetof(LineInfo, line) instead of storing the attribute twice.

[corona10]

@kmod Thanks That's reasonable.

[undingen]

Thanks for the change! 👍