Why is __getslice__ still implemented?

James Stroud jstroud at mbi.ucla.edu
Tue Apr 10 12:24:02 CEST 2007


Torsten Bronger wrote:
> Hallöchen!
> 
> According to <http://docs.python.org/ref/sequence-methods.html>,
> __getslice__ is deprecated.  At the moment, I derive an own class
> from unicode and want to implement my own slicing.  I found that I
> have to override __getslice__ since __getitem__ isn't called when I
> have something like my_instance[a:b] in my code.
> 
> According to
> <news:mailman.7438.1102640455.5135.python-list at python.org>, this may
> have efficiency reasons, however, I agree with
> news:1102645919.114898.139820 at f14g2000cwb.googlegroups.com that this
> is quite confusing.  It forces people to implement a deprecated
> function after all.  I think the docs should say that you still have
> to override __getslice__ when subclassing from a built-in type,
> unless I really don't understand the issue correctly.
> 
> Tschö,
> Torsten.
> 

Which version of python are you using?

chernev 20% /sw/bin/python
Python 2.5 (r25:51908, Oct 10 2006, 03:45:47)
[GCC 4.0.1 (Apple Computer, Inc. build 5363)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
py> class Bob(object):
...   def __getitem__(self, *args):
...     print args
...
py> b = Bob()
py> b[4:21:2]
(slice(4, 21, 2),)
py> b[5:18:21,2:9:2,8,14:4]
((slice(5, 18, 21), slice(2, 9, 2), 8, slice(14, 4, None)),)



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