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| References | (4 earlier) <CAPTjJmp=b2ZA8eqvyf3tqK+0MHqOgS-PAG+ELNNOwuKKPq4FJQ@mail.gmail.com> <mailman.18488.1423127457.18130.python-list@python.org> <54d33aa6$0$13003$c3e8da3$5496439d@news.astraweb.com> <CALwzidnG7gPEe3d3AUMA8B7XZNE48SzeNK+DSdwYKuiGiU7PUg@mail.gmail.com> <CABicbJ+DKbWgR2jGYTCvTLQD6s3TDd7KD6p=xLYD=rxetd71-Q@mail.gmail.com> |
|---|---|
| Date | 2015-02-06 12:17 +1100 |
| Subject | Re: meaning of: line, = |
| From | Chris Angelico <rosuav@gmail.com> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.18499.1423185454.18130.python-list@python.org> (permalink) |
On Fri, Feb 6, 2015 at 12:12 PM, Devin Jeanpierre
<jeanpierreda@gmail.com> wrote:
> Here's another example, one that still exists in Python 3:
>
>>>> [] = ''
>>>> () = ''
> File "<stdin>", line 1
> SyntaxError: can't assign to ()
>
> The syntax explicitly blacklists (), but forgets to blacklist [].
So... this is actually a really really obscure little feature.
[] = x
# is equivalent to
try: next(iter(x))
except StopIteration: pass
else: raise ValueError("too many values to unpack (expected 0)")
It's a way of asserting that an iterator is exhausted! Perfect code
snippet for your next International Obfuscated Python Code Contest
entry.
ChrisA
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Re: meaning of: line, = Albert-Jan Roskam <fomcl@yahoo.com> - 2015-02-04 14:38 +0000
Re: meaning of: line, = Rustom Mody <rustompmody@gmail.com> - 2015-02-04 07:09 -0800
Re: meaning of: line, = Peter Otten <__peter__@web.de> - 2015-02-04 18:36 +0100
Re: meaning of: line, = Chris Angelico <rosuav@gmail.com> - 2015-02-05 08:18 +1100
Re: meaning of: line, = Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-02-05 01:10 -0800
Re: meaning of: line, = Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-02-05 20:40 +1100
Re: meaning of: line, = Ian Kelly <ian.g.kelly@gmail.com> - 2015-02-05 09:08 -0700
Re: meaning of: line, = Rustom Mody <rustompmody@gmail.com> - 2015-02-05 08:45 -0800
Re: meaning of: line, = Skip Montanaro <skip.montanaro@gmail.com> - 2015-02-05 10:56 -0600
Re: meaning of: line, = Tim Chase <python.list@tim.thechases.com> - 2015-02-05 11:00 -0600
Re: meaning of: line, = Rustom Mody <rustompmody@gmail.com> - 2015-02-05 08:59 -0800
Re: meaning of: line, = Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-02-06 05:09 -0800
Re: meaning of: line, = Rustom Mody <rustompmody@gmail.com> - 2015-02-06 05:20 -0800
Re: meaning of: line, = Rustom Mody <rustompmody@gmail.com> - 2015-02-06 06:03 -0800
Re: meaning of: line, = Tim Chase <python.list@tim.thechases.com> - 2015-02-05 10:21 -0600
Re: meaning of: line, = Devin Jeanpierre <jeanpierreda@gmail.com> - 2015-02-05 17:12 -0800
Re: meaning of: line, = Chris Angelico <rosuav@gmail.com> - 2015-02-06 12:17 +1100
Re: meaning of: line, = Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-02-06 17:52 +1300
Re: meaning of: line, = Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2015-02-06 12:30 +1300
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