[Python-ideas] Unpack of sequences

[M.-A. Lemburg]

Guido van Rossum wrote:
> Also it won't work in Python 3.

The star import is only used to trigger a call to PyFrame_LocalsToFast().

In Python 3, the only way to trigger such a call is by using
a call level trace function... or by exposing the C function
in Python.

> On Wed, Aug 29, 2012 at 11:50 AM, M.-A. Lemburg <mal at egenix.com> wrote:
>> Steven D'Aprano wrote:
>>> On 30/08/12 04:16, M.-A. Lemburg wrote:
>>>
>>>>>>> d = dict(a=1, b=2, c=3)
>>>>>>> locals().update(d)
>>>>>>> a
>>>> 1
>>>>>>> b
>>>> 2
>>>>>>> c
>>>> 3
>>>>
>>>> Not that I'd recommend doing this, but it's possible :-)
>>>
>>>
>>> Try it inside a function.
>>>
>>>
>>> py> def test():
>>> ...     d = dict(a=1, b=2, c=3)
>>> ...     locals().update(d)
>>> ...     print a
>>> ...
>>> py> test()
>>> Traceback (most recent call last):
>>>   File "<stdin>", line 1, in <module>
>>>   File "<stdin>", line 4, in test
>>> NameError: global name 'a' is not defined
>>
>> Yeah, that's because functions use fast locals, which locals()
>> only mirrors as dictionary.
>>
>> You have to play some tricks to it work...
>>
>> def f(d):
>>     from test import *
>>     locals().update(d)
>>     print a,b,c
>>
>> d = dict(a=1, b=2, c=3)
>> f(d)
>>
>> ...and because you're not supposed to do this, you get a SyntaxWarning :-)
>>
>> --
>> Marc-Andre Lemburg
>> eGenix.com
>>
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>>
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> 
> 
> 

-- 
Marc-Andre Lemburg
eGenix.com

Professional Python Services directly from the Source  (#1, Aug 29 2012)
>>> Python/Zope Consulting and Support ...        http://www.egenix.com/
>>> mxODBC.Zope.Database.Adapter ...             http://zope.egenix.com/
>>> mxODBC, mxDateTime, mxTextTools ...        http://python.egenix.com/
________________________________________________________________________
2012-10-23: Python Meeting Duesseldorf ...                 55 days to go
2012-08-28: Released mxODBC 3.2.0 ...             http://egenix.com/go31
2012-08-20: Released mxODBC.Connect 2.0.0 ...     http://egenix.com/go30

::: Try our new mxODBC.Connect Python Database Interface for free ! ::::


   eGenix.com Software, Skills and Services GmbH  Pastor-Loeh-Str.48
    D-40764 Langenfeld, Germany. CEO Dipl.-Math. Marc-Andre Lemburg
           Registered at Amtsgericht Duesseldorf: HRB 46611
               http://www.egenix.com/company/contact/