Chris Angelico, 21.02.2014 04:15: > Just as PEP 308 introduced a means of value-based conditions in an > expression, this system allows exception-based conditions to be used > as part of an expression. > [...] > This currently works:: > > lst = [1, 2, None, 3] > value = lst[2] or "No value" > > The proposal adds this:: > > lst = [1, 2] > value = lst[2] except IndexError: "No value"
I see a risk of interfering with in-place assignment operators, e.g. x /= y except ZeroDivisionError: 1 might not do what one could expect, because (as I assume) it would behave differently from x = x / y except ZeroDivisionError: 1 I think that falls under the "overly broad exception handling" issue. If you want to include the assignment, you'll have to spell out the try-except block yourself. I find the difference in the two behaviours very unfortunate, though. This also reduces the scope of applicability somewhat. Cython has typed assignments, so a straight forward idea would be to handle TypeErrors in assignments like this: cdef str s s = x except TypeError: str(x) However, I guess that would similarly counter the idea of exception handling in an *expression*, and the correct and non-ambiguous way to do this would be to spell out the try-except block. Summing it up, my impression is that it helps some use cases but leaves others more ambiguous/unclear/unfortunate, which makes me lean towards rejecting it. Stefan _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com