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Re: try..except with empty exceptions

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On 11/04/15 08:11, Steven D'Aprano wrote:
> But with try...except, an empty exception list means to catch
> *everything*, not nothing:
> 
> try: ... except a,b,c: # catches a, b, c
> 
> try: ... except a,b: # catches a, b

This example is incorrect. In python3 it is a SyntaxError:

    Python 3.4.0 (default, Apr 11 2014, 13:05:11)
    [GCC 4.8.2] on linux
    Type "help", "copyright", "credits" or "license" for more
    information.
    >>> try:
    ...  1/0
    ... except ValueError, ZeroDivisionError:
      File "<stdin>", line 3
        except ValueError, ZeroDivisionError:
                         ^
    SyntaxError: invalid syntax

In python2 it aliases ValueError as ZeroDivisionError:

    Python 2.7.6 (default, Mar 22 2014, 22:59:56)
    [GCC 4.8.2] on linux2
    Type "help", "copyright", "credits" or "license" for more
    information.
    >>> try:
    ...  1/0
    ... except ValueError, ZeroDivisionError:
    ...  pass
    ...
    Traceback (most recent call last):
      File "<stdin>", line 2, in <module>
    ZeroDivisionError: integer division or modulo by zero

To get the behaviour you expect, you must use parentheses:

    >>> try:
    ...  1/0
    ... except (ValueError, ZeroDivisionError):
    ...  pass
    ...

Regards,
Ian F
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try..except with empty exceptions Pavel S <pavel@schon.cz> - 2015-04-10 01:48 -0700
  Re: try..except with empty exceptions Chris Angelico <rosuav@gmail.com> - 2015-04-10 18:58 +1000
  Re: try..except with empty exceptions sohcahtoa82@gmail.com - 2015-04-10 12:31 -0700
    Re: try..except with empty exceptions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 11:42 +1000
      Re: try..except with empty exceptions Dave Angel <davea@davea.name> - 2015-04-10 22:23 -0400
        Re: try..except with empty exceptions Rustom Mody <rustompmody@gmail.com> - 2015-04-10 19:38 -0700
          Re: try..except with empty exceptions Dave Angel <davea@davea.name> - 2015-04-10 23:46 -0400
            Re: try..except with empty exceptions Rustom Mody <rustompmody@gmail.com> - 2015-04-10 21:17 -0700
              Re: try..except with empty exceptions Rustom Mody <rustompmody@gmail.com> - 2015-04-10 21:39 -0700
          Re: try..except with empty exceptions Cameron Simpson <cs@zip.com.au> - 2015-04-11 19:27 +1000
            Re: try..except with empty exceptions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 21:00 +1000
              Re: try..except with empty exceptions Chris Angelico <rosuav@gmail.com> - 2015-04-11 21:21 +1000
              Re: try..except with empty exceptions Ian Kelly <ian.g.kelly@gmail.com> - 2015-04-11 12:49 -0600
              Re: try..except with empty exceptions Chris Angelico <rosuav@gmail.com> - 2015-04-12 06:04 +1000
              Re: try..except with empty exceptions Chris Angelico <rosuav@gmail.com> - 2015-04-12 06:05 +1000
        Re: try..except with empty exceptions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 17:11 +1000
          Re: try..except with empty exceptions Serhiy Storchaka <storchaka@gmail.com> - 2015-04-11 11:22 +0300
            Re: try..except with empty exceptions Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-04-11 20:47 +1000
          Re: try..except with empty exceptions Dave Angel <davea@davea.name> - 2015-04-11 06:14 -0400
          Re: try..except with empty exceptions Dave Angel <davea@davea.name> - 2015-04-11 06:24 -0400
          Re: try..except with empty exceptions Ian Foote <ian@feete.org> - 2015-04-11 15:20 +0100
      Re: try..except with empty exceptions Terry Reedy <tjreedy@udel.edu> - 2015-04-11 04:58 -0400
  Re: try..except with empty exceptions Dave Angel <davea@davea.name> - 2015-04-10 16:27 -0400
  Re: try..except with empty exceptions Rustom Mody <rustompmody@gmail.com> - 2015-04-10 18:56 -0700

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