all Python 3disfunction

dis.distb()

disassembly

Disassembles the frame where an exception was raised and marks the failing instruction with a --> arrow.

Syntax

dis.distb(tb=None, *, file=None)

Without an argument it uses sys.last_traceback, which is set only in an interactive session after an unhandled error — in a script distb() raises RuntimeError "no last traceback to disassemble". Inside except pass the traceback explicitly: sys.exc_info()[2] or e.__traceback__. The arrow tells you which operation of a long line failed — say, which of several subscripts went out of range.

Examples

import dis, io
try:
    [1, 2][5]
except IndexError as e:
    buf = io.StringIO()
    dis.distb(e.__traceback__, file=buf)
    print('-->' in buf.getvalue())  # → True

import dis
try:
    dis.distb()
except RuntimeError as e:
    print(e)  # → no last traceback to disassemble

See also

Common errors

Open in the full glossarydocs.python.orgReport an inaccuracy