[Python-Dev] Chaining seq1.pop().extend(seq2) does give wrong
result
Sjoerd Mullender
sjoerd at acm.org
Tue Mar 23 10:04:34 EST 2004
Jacek Trzmiel wrote:
> Hi,
>
> $ python
> Python 2.3.2 (#1, Dec 5 2003, 03:04:50)
> [GCC 3.3.3 [FreeBSD] 20031106] on freebsd5
> Type "help", "copyright", "credits" or "license" for more information.
>
>>>>stack = [[1], [2]]
>>>>fields = [3]
>>>>out = stack.pop()
>>>>out.extend(fields)
>>>>print out
>
> [2, 3]
>
>>>>stack = [[1], [2]]
>>>>fields = [3]
>>>>out = stack.pop().extend(fields)
>>>>print out
>
> None
>
>
> Shouldn't those two give identical result?
No. somelist.extend() changes somelist but doesn't return a value (in
other words, it returns None, which is exactly what you're seeing).
Also, this is not really appropriate for python-dev, but rather for
python-list, I would think.
--
Sjoerd Mullender <sjoerd at acm.org>
More information about the Python-Dev
mailing list