Re: [gentoo-dev] Stabilization of Python 3.1

[Arfrever Frehtes Taifersar Arahesis <Arfrever@gentoo.org>]

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2009-09-20 19:30:54 Nirbheek Chauhan napisał(a):
> On Sun, Sep 20, 2009 at 8:54 PM, Arfrever Frehtes Taifersar Arahesis
> <Arfrever@gentoo.org> wrote:
> > 2009-09-20 16:53:37 Jesús Guerrero napisał(a):
> >> # eselect python set 2
> >> # emerge -s foo
> >>   File "/usr/bin/emerge", line 41
> >>     except PermissionDenied, e:
> >>                            ^
> >> SyntaxError: invalid syntax
> >>
> >>
> >> Ummm, yes, it works *beautifully*, you see. Nothing else to add.
> >
> > I have fixed it today :) .
> > http://sources.gentoo.org/viewcvs.py/portage?rev=14289&view=rev
> 
> This is silly. portage itself was broken with python-3.1 and you want
> to stabilize it?

You should distinguish between Python version used by Portage and
Python version used by packages which can be installed by Portage.

> Actually, how did you make portage work with both 2.x and 3.x at the
> same time?

Portage doesn't yet work with Python 3, but it hopefully change soon.

> I would be very interested to know this since afaik no useful program
> can work with both python-3 and python-2 with the same code.

It isn't hard to write code which works with both Python 2.6 and 3.*.

Example:

$ cat get_protocol.py
#!/usr/bin/env python

# It allows to use print() function in 2.6.
from __future__ import print_function

import sys

try:
  # Python 3
  from urllib.parse import urlparse as urllib_parse_urlparse
except ImportError:
  # Python 2
  from urlparse import urlparse as urllib_parse_urlparse

if len(sys.argv) != 2:
  sys.stderr.write("This script requires 1 argument: URL\n")

def get_protocol(url):
  return urllib_parse_urlparse(url)[0]

print("Protocol:", get_protocol(sys.argv[1]))
$ ./get_protocol.py http://www.example.com
Protocol: http

-- 
Arfrever Frehtes Taifersar Arahesis

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