[Python-Dev] Chaining seq1.pop().extend(seq2) does give wrong result (original) (raw)

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>



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