[Python-Dev] PEP for Better Control of Nested Lexical Scopes

[Ron Adam]

Jeremy Hylton wrote:
> On 2/21/06, Jeremy Hylton <jeremy at alum.mit.edu> wrote:
>> I had to lookup top-post :-).
>>
>> On 2/21/06, Bengt Richter <bokr at oz.net> wrote:
>>> On Tue, 21 Feb 2006 08:02:08 -0500, "Jeremy Hylton" <jeremy at alum.mit.edu> wrote:
>>>> Jeremy
>>> Hey, only Guido is allowed to top-post. He said so ;-)
>> The Gmail UI makes it really easy to forget where the q
> 
> Sorry about that.  Hit the send key by mistake.
> 
> The Gmail UI makes it really easy to forget where the quoted text is
> in relation to your own text.
> 
>>> But to the topic, it just occurred to me that any outer scopes could be given names
>>> (including global namespace, but that would have the name global by default, so
>>> global.x would essentially mean what globals()['x'] means now, except it would
>>> be a name error if x didn't pre-exist when accessed via namespace_name.name_in_space notation.
> 
> Isn't this suggestion that same as Greg Ewing's?
> 
>>>     namespace g_alias  # g_alias.x becomes alternate spelling of global.x
>>>     def outer():
>>>         namespace mezzanine
>>>         a = 123
>>>         print a  # => 123
>>>         print mezzanine.a  # => 123 (the name space name is visible and functional locally)
>>>         def inner():
>>>             print mezzanine.a => 123
>>>             mezznine.a =456
>>>         inner()
>>>         print a # = 456
>>>         global.x = re-binds global x, name error if not preexisting.
>>>
>>> This would allow creating mezzanine like an attribute view of the slots in that local namespace,
>>> as well as making namespace itself visible there, so the access to mezzanine would look like a read access to
>>> an ordinary object named mezzanine that happened to have attribute slots matching outer's local name space.

Why not just use a class?


def incgen(start=0, inc=1) :
    class incrementer(object):
      a = start - inc
      def __call__(self):
         self.a += inc
         return self.a
    return incrementer()

a = incgen(7, 5)
for n in range(10):
    print a(),


7 12 17 22 27 32 37 42 47 52


Cheers,
    Ronald Adam