[Python-bugs-list] [ python-Bugs-473985 ] str, getitem and slices (original) (raw)

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Tue, 23 Oct 2001 07:05:03 -0700

Bugs item #473985, was opened at 2001-10-23 03:39 You can respond by visiting: http://sourceforge.net/tracker/?func=detail&atid=105470&aid=473985&group_id=5470

Category: None Group: None Status: Open Resolution: Invalid Priority: 5 Submitted By: Walter D�rwald (doerwalter) Assigned to: Nobody/Anonymous (nobody) Summary: str, getitem and slices

Initial Comment: Using slices with getitem doesn't work with classes derived from str:

class S(str): def getitem(self, index): print "getitem", index return str.getitem(self, index) def setitem(self, index, value): print "setitem", index, value

s = S("foo") print s[0] print s[0:2] s[0] = "b" s[0:2] = "bar"

This prints:

getitem 0 f fo setitem 0 b setitem slice(0, 2, None) bar

instead of

getitem 0 f getitem slice(0, 2, None) fo setitem 0 b setitem slice(0, 2, None) bar

i.e. when no getslice is defined s[0:2] will not be forwarded to getitem, but it seems to work for setitem.

Comment By: Walter D�rwald (doerwalter) Date: 2001-10-23 07:05

Message: Logged In: YES user_id=89016

Oops, this wasn't meant to be a patch. Should have gone into the bugs category.

The problems is that http://python.sourceforge.net/devel- docs/ref/sequence-methods.html says, that getslice is "Deprecated since release 2.0", so the user will want to implement getslice via getitem.

Comment By: Guido van Rossum (gvanrossum) Date: 2001-10-23 06:48

Message: Logged In: YES user_id=6380

I don't think this is a bug. S inherits getslice from the str base class, but since str is immutable, it doesn't define a setslice to inherit for S.

BTW I'm reclassifying this as a bug, not a patch. This will unfortunately invalidate the old URL you had for this entry (SF doesn't really like reclassification that much.)

You can respond by visiting: http://sourceforge.net/tracker/?func=detail&atid=105470&aid=473985&group_id=5470