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Re: The binding operator, and what gets bound to what

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On Fri, Dec 5, 2014 at 11:34 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
>> I don't think this is implementation-dependent.
>
> The docs say that it is:
>
> https://docs.python.org/3/reference/simple_stmts.html#the-global-statement
>
>     Names listed in a global statement MUST NOT [emphasis added] be
>     defined as formal parameters or in a for loop control target,
>     class definition, function definition, or import statement.
>
>     CPython implementation detail: The current implementation does not
>     enforce the two restrictions, but programs should not abuse this
>     freedom, as future implementations may enforce them or silently
>     change the meaning of the program.

Interesting, I didn't know that either.

But the first restriction _is_ enforced:

rosuav@sikorsky:~$ python3
Python 3.5.0a0 (default:23ab1197df0b, Nov 20 2014, 12:57:44)
[GCC 4.7.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> def x(y):
...     global y
...
  File "<stdin>", line 2
SyntaxError: name 'y' is parameter and global

Likewise in CPython 2.7:

rosuav@sikorsky:~$ python
Python 2.7.3 (default, Mar 13 2014, 11:03:55)
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> def x(y):
...     global y
...
  File "<stdin>", line 1
SyntaxError: name 'y' is local and global

ChrisA

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Thread

About Modifying Globals LJ <luisjosenovoa@gmail.com> - 2014-12-04 12:09 -0800
  Re: About Modifying Globals Chris Angelico <rosuav@gmail.com> - 2014-12-05 07:22 +1100
  Re: About Modifying Globals Ian Kelly <ian.g.kelly@gmail.com> - 2014-12-04 13:21 -0700
  Re: About Modifying Globals Dave Angel <davea@davea.name> - 2014-12-04 18:54 -0500
  Re: About Modifying Globals Chris Angelico <rosuav@gmail.com> - 2014-12-05 10:58 +1100
  Re: About Modifying Globals Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 13:09 +1100
    The binding operator, and what gets bound to what (was: About Modifying Globals) Ben Finney <ben+python@benfinney.id.au> - 2014-12-05 16:36 +1100
      Re: The binding operator, and what gets bound to what (was: About Modifying Globals) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 20:53 +1100
        Re: The binding operator, and what gets bound to what (was: About Modifying Globals) Chris Angelico <rosuav@gmail.com> - 2014-12-05 21:03 +1100
          Re: The binding operator, and what gets bound to what (was: About Modifying Globals) Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 23:26 +1100
            Re: The binding operator, and what gets bound to what (was: About Modifying Globals) Chris Angelico <rosuav@gmail.com> - 2014-12-05 23:42 +1100
        Re: The binding operator, and what gets bound to what Ned Batchelder <ned@nedbatchelder.com> - 2014-12-05 07:06 -0500
          Re: The binding operator, and what gets bound to what Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-05 23:34 +1100
            Re: The binding operator, and what gets bound to what Chris Angelico <rosuav@gmail.com> - 2014-12-05 23:48 +1100
            Re: The binding operator, and what gets bound to what Ned Batchelder <ned@nedbatchelder.com> - 2014-12-05 07:56 -0500
  Re: About Modifying Globals "shiyao.ma" <i@introo.me> - 2014-12-05 10:53 +0800

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