L[:]

Date	2014-01-10 09:38 -0800
From	Albert-Jan Roskam <fomcl@yahoo.com>
Subject	L[:]
Newsgroups	comp.lang.python
Message-ID	<mailman.5305.1389387570.18130.python-list@python.org> (permalink)

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In Python Cookbook, one of the authors (I forgot who) consistently used the "L[:]" idiom like below. If the second line simply starts with "L =" (so no "[:]") only the name "L" would be rebound, not the underlying object. That was the authorś explanation as far as I can remember. I do not get that. Why is the "L[:]" idiom more memory-efficient here? How could the increased efficiency be demonstrated?

#Python 2.7.3 (default, Sep 26 2013, 16:38:10) [GCC 4.7.2] on linux2
>>> L = [x ** 2 for x in range(10)]
>>> L[:] = ["foo_" + str(x) for x in L]


Thanks!


Regards,

Albert-Jan



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L[:] Albert-Jan Roskam <fomcl@yahoo.com> - 2014-01-10 09:38 -0800

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