Path: csiph.com!x330-a1.tempe.blueboxinc.net!usenet.pasdenom.info!aioe.org!feeder.news-service.com!newsfeed.xs4all.nl!newsfeed6.news.xs4all.nl!xs4all!post.news.xs4all.nl!not-for-mail
Return-Path: <ericsnowcurrently@gmail.com>
X-Original-To: python-list@python.org
Delivered-To: python-list@mail.python.org
X-Spam-Status: OK 0.006
X-Spam-Evidence: '*H*': 0.99; '*S*': 0.00; '2.7': 0.04; 'subject:code': 0.07; 'subject:object': 0.07; '%s"': 0.09; 'subject:2.7': 0.09; 'tuple': 0.09; 'variables.': 0.09; 'def': 0.15; "'w',": 0.16; '(name,': 0.16; '**kwargs):': 0.16; '*args,': 0.16; '2.7:': 0.16; 'attributes:': 0.16; 'incomplete': 0.16; 'subject:between': 0.16; 'superfluous': 0.16; 'variables;': 0.16; 'thanks!': 0.16; '>>>': 0.18; 'arguments': 0.18; 'to:name:python- list': 0.18; 'seems': 0.20; 'update.': 0.24; 'code': 0.25; 'guess': 0.26; 'up.': 0.26; 'tried': 0.26; 'function': 0.27; 'version,': 0.28; 'message-id:@mail.gmail.com': 0.29; 'module': 0.30; '3.x': 0.30; 'arguments.': 0.30; 'url:dev': 0.30; 'url:library': 0.31; 'list': 0.32; 'anyone': 0.32; 'actually': 0.33; 'probably': 0.33; 'there': 0.33; 'to:addr:python-list': 0.33; 'wondering': 0.33; 'difference': 0.34; 'however,': 0.34; 'doc': 0.34; 'exercises': 0.34; 'object': 0.35; 'url:python': 0.36; 'several': 0.37; 'but': 0.37; 'could': 0.38; 'received:google.com': 0.38; 'url:org': 0.38; 'received:209.85': 0.38; 'url:docs': 0.39; 'listing': 0.39; 'why': 0.39; 'to:addr:python.org': 0.39; 'description': 0.39; "it's": 0.40; 'results': 0.61; 'closed': 0.62; 'free': 0.63; 'here': 0.65; 'received:209.85.215.174': 0.67; 'received:mail- ey0-f174.google.com': 0.67; 'skip:b 50': 0.67; 'care': 0.71; '[3]': 0.73; '3.3': 0.84; 'compose': 0.84; 'differences,': 0.84
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:date:message-id:subject:from:to:content-type; bh=LquQyQjY7Fp0A+nHhyXmbZKeh1jXw8ShQdDN53JeEx8=; b=UKSh5nBGoe9knfScbvFfk54IH3iM0O9NjLkmlvJuhBfJzX+gh+czkrGpSC7M6Ksn1g 5AxrXDj/qHzwPaYBmiuOkSwqTY8Cm0KCInCs29rOA9X8rpItxQfpx0izdi7oFHT/fEH2 /hdCje7ccfIuaaLH8BS5tgDpIDB5vtzFHdwJY=
MIME-Version: 1.0
Date: Wed, 10 Aug 2011 18:38:17 -0600
Subject: code object differences between 2.7 and 3.3a
From: Eric Snow <ericsnowcurrently@gmail.com>
To: python-list <python-list@python.org>
Content-Type: text/plain; charset=ISO-8859-1
X-BeenThere: python-list@python.org
X-Mailman-Version: 2.1.12
Precedence: list
List-Id: General discussion list for the Python programming language <python-list.python.org>
List-Unsubscribe: <http://mail.python.org/mailman/options/python-list>, <mailto:python-list-request@python.org?subject=unsubscribe>
List-Archive: <http://mail.python.org/pipermail/python-list>
List-Post: <mailto:python-list@python.org>
List-Help: <mailto:python-list-request@python.org?subject=help>
List-Subscribe: <http://mail.python.org/mailman/listinfo/python-list>, <mailto:python-list-request@python.org?subject=subscribe>
Newsgroups: comp.lang.python
Message-ID: <mailman.2134.1313023099.1164.python-list@python.org>
Lines: 79
NNTP-Posting-Host: 2001:888:2000:d::a6
X-Trace: 1313023099 news.xs4all.nl 23923 [2001:888:2000:d::a6]:39672
X-Complaints-To: abuse@xs4all.nl
Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:11160

Specifically, I am wondering why there is a difference for co_names.
Here is a function that exercises the different code object pieces[1]:

def g(y=5):
   a = 7
   def f(x, w=y, z=4, *args, **kwargs):
      b = a
      c = global_x
   return f

f1 = g()


Here are the results for 2.7:

>>> for name in dir(f1.func_code): print("%s -> %s" % (name, getattr(f1.func_code, name)))
...
co_argcount -> 3
co_cellvars -> ()
co_code -> }t}dS
co_consts -> (None,)
co_filename -> <stdin>
co_firstlineno -> 3
co_flags -> 15
co_freevars -> ('a',)
co_lnotab ->
co_name -> f
co_names -> ('a', 'b', 'global_x', 'c')
co_nlocals -> 7
co_stacksize -> 1
co_varnames -> ('x', 'w', 'z', 'args', 'kwargs', 'c', 'b')


And for 3.3:

>>> for name in dir(f1.__code__): print("%s -> %s" % (name, getattr(f1.__code__, name)))
...
co_argcount -> 3
co_cellvars -> ()
co_code -> b'\x88\x00\x00}\x05\x00t\x00\x00}\x06\x00d\x00\x00S'
co_consts -> (None,)
co_filename -> <stdin>
co_firstlineno -> 3
co_flags -> 31
co_freevars -> ('a',)
co_kwonlyargcount -> 0
co_lnotab -> b'\x00\x01\x06\x01'
co_name -> f
co_names -> ('global_x',)
co_nlocals -> 7
co_stacksize -> 1
co_varnames -> ('x', 'w', 'z', 'args', 'kwargs', 'b', 'c')


While there are several differences, the one I care about is co_name.
For 2.7 it's what I would expect.  However, for 3.3 it's not[2][3].
It is actually nicer for my application this way, but I want to verify
the situation before I get me hopes up. :)

Before I go email-list-diving or digging through PyEval_EvalCodeEx,  I
wanted to see if anyone has any insight about this change in co_names.
 Thanks!

-eric


[1] yes, 3.x also supports keyword-only arguments.  I tried this on
3.3 with extra kw-only arguments and it was the same outcome.
[2] The documentation for the inspect module gives an incomplete
listing of the code object attributes:
<http://docs.python.org/dev/library/inspect.html>  The description of
co_names there ("tuple of names of local variables") seems
inconsistent with what I am seeing.  It's probably just that I am
misinterpreting that list or the doc needs an update.
[3] My guess is that co_names was seen as bloated and the superfluous
items removed, leaving only the un-closed free variables; co_freevars
is the closed free variables.  To get the same tuple as the 2.7
version, you could compose it from co_freevars, co_names, and the end
of co_varnames.