Lack of whitespace between contain operator ("in") and other expression tokens doesn't result in SyntaxError: bug or feature?

[Dan Stromberg]

On Thu, May 3, 2012 at 12:21 PM, Garrett Cooper <yanegomi at gmail.com> wrote:

> On Thu, May 3, 2012 at 12:03 PM, Ian Kelly <ian.g.kelly at gmail.com> wrote:
> > On Thu, May 3, 2012 at 12:49 PM, Garrett Cooper <yanegomi at gmail.com>
> wrote:
> >>    I was wondering whether this was a parser bug or feature (seems
> >> like a bug, in particular because it implicitly encourages bad syntax,
> >> but I could be wrong). The grammar notes (for 2.7 at least [1]) don't
> >> seem to explicitly require a space between 'in' and another parser
> >> token (reserved work, expression, operand, etc), but I could be
> >> misreading the documentation.
> >
> > The grammar doesn't require whitespace there.  It tends to be flexible
> > about whitespace wherever it's not necessary to resolve ambiguity.
> >
> >>>> x = [3, 2, 1]
> >>>> x [0]if x [1]else x [2]
> > 3
> >>>> 1 . real
> > 1
> >>>> 1.5.real
> > 1.5
>
>     Sure.. it's just somewhat inconsistent with other expectations in
> other languages, and seems somewhat unpythonic.
>    Not really a big deal (if it was I would have filed a bug
> instead), but this was definitely a bit confusing when I ran it
> through the interpreter a couple of times...
> Thanks!
> -Garrett
> --
> http://mail.python.org/mailman/listinfo/python-list
>

For the code prettiness police, check out pep8 and/or pylint.  I highly
value pylint for projects more than a couple hundred lines.

For the whitespace matter that's been beaten to death:
http://stromberg.dnsalias.org/~strombrg/significant-whitespace.html

I'll include one issue about whitespace here.  In FORTRAN 77, the following
two statements look very similar, but have completely different meanings,
because FORTRAN had too little significant whitespace:

DO10I=1,10
DO10I=1.10

The first is the start of a loop, the second is an assignment statement.
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