Re: Python Iterables struggling using map() built-in

From	Gregory Ewing <greg.ewing@canterbury.ac.nz>
Newsgroups	comp.lang.python
Subject	Re: Python Iterables struggling using map() built-in
Date	2014-12-08 18:06 +1300
Message-ID	<cekpv7FsqeoU1@mid.individual.net> (permalink)
References	(2 earlier) <CALwzid=79=i3Sez3fQYV7xU2bEAL4_ohPqxhuYj59Y5ihXk1Zg@mail.gmail.com> <mailman.16685.1417976998.18130.python-list@python.org> <5484e3d8$0$13013$c3e8da3$5496439d@news.astraweb.com> <roy-3F4751.19122007122014@news.panix.com> <mailman.16692.1417999114.18130.python-list@python.org>

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Terry Reedy wrote:
> However, this 'beautiful' code has a trap.  If one gets rid of the 
> seemingly unneeded temporary list res by telescoping the last two lines 
> into a bit too much into
> 
>             yield tuple(next(i) for i in iters)
> 
> we now have an infinite generator, because tuple() swallows the 
> StopIteration raised as a side-effect of next calls.

An excellent example of the kind of thing that PEP 479
is designed to catch! There couldn't be a better
advertisement for it. :-)

-- 
Greg

Thread

Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 05:29 +1100
  Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-08 10:33 +1100
    Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 10:50 +1100
      Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:27 -0500
        Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 11:35 +1100
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-08 09:40 +0000
            Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 20:50 +1100
            Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-08 19:02 -0500
    Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:12 -0500
      Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 11:34 +1100
        Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-07 19:45 -0500
          Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-08 12:00 +1100
          Re: Python Iterables struggling using map() built-in MRAB <python@mrabarnett.plus.com> - 2014-12-08 03:09 +0000
      Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-07 19:38 -0500
        Re: Python Iterables struggling using map() built-in Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-12-08 18:06 +1300
      Re: Python Iterables struggling using map() built-in Ned Batchelder <ned@nedbatchelder.com> - 2014-12-07 20:06 -0500
      Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-09 13:50 +1100
        Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-09 00:03 -0500
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-09 06:40 +0000
        Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-09 15:06 -0500
          Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-10 11:10 +1100
            Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-10 11:20 +1100
            Re: Python Iterables struggling using map() built-in Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-12-10 00:24 +0000
            Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-09 21:44 -0500
              Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-10 09:24 +0000
                Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-10 20:32 +1100
                Re: Python Iterables struggling using map() built-in Marko Rauhamaa <marko@pacujo.net> - 2014-12-10 12:58 +0200
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-10 09:46 -0700
                Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve@pearwood.info> - 2014-12-11 04:01 +0000
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-11 15:00 -0700
                Re: Python Iterables struggling using map() built-in Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-12 10:28 +1100
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-11 16:57 -0700
                Re: Python Iterables struggling using map() built-in Roy Smith <roy@panix.com> - 2014-12-11 20:55 -0500
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-12 00:36 -0700
                Re: Python Iterables struggling using map() built-in Chris Angelico <rosuav@gmail.com> - 2014-12-12 11:44 +1100
                Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-10 12:48 -0500
                Re: Python Iterables struggling using map() built-in Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-10 13:32 -0700
                Re: Python Iterables struggling using map() built-in Terry Reedy <tjreedy@udel.edu> - 2014-12-10 23:17 -0500
    Re: Python Iterables struggling using map() built-in Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-12-08 18:00 +1300

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