[issue14178] _elementtree problem deleting slices with steps != +1
Roundup Robot devn...@psf.upfronthosting.co.za added the comment: New changeset 1a721b9a4039 by Eli Bendersky in branch 'default': Issue #14178: Problem deleting slices with steps != +1 in the _elementtree module. http://hg.python.org/cpython/rev/1a721b9a4039 -- nosy: +python-dev ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14178 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14178] _elementtree problem deleting slices with steps != +1
Changes by Eli Bendersky eli...@gmail.com: -- resolution: - fixed stage: patch review - committed/rejected status: open - closed ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14178 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue14178] _elementtree problem deleting slices with steps != +1
Eli Bendersky eli...@gmail.com added the comment: WRT the ParseError problem, I've opened issue #14207 for it since the problems are quite unrelated. -- title: Failing tests for ElementTree - _elementtree problem deleting slices with steps != +1 ___ Python tracker rep...@bugs.python.org http://bugs.python.org/issue14178 ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
Problem with slices.
I'm for the moment writing two classes.
A table, which is like a list, but can start at any integer.
A tree which is like a dictionary, but will iterate over the
keys in sorted order.
The problem is that I would like to implemet slices but, that
seems to be impossible with how slices are implemented now.
I wrote the following class to test things out.
class Tst:
def __getitem__(self, key):
print key
then I called the interpreter and got this:
from tst import Tst
t=Tst()
t[:]
slice(0, 2147483647, None)
t[:9]
slice(0, 9, None)
t[:'ok']
slice(None, 'ok', None)
t['ok':]
slice('ok', None, None)
t[6:]
slice(6, 2147483647, None)
t[1,2]
(1, 2)
t[1,2:]
(1, slice(2, None, None))
t[(1,2):]
slice((1, 2), None, None)
Now suppose tab is a table with indexes from -5 to 12.
tab[:4] would have to make a table ranging from -5 to 4
tab[0:4] would have to make a table ranging from 0 to 4.
But each time I would be given the same argument, being
slice(0, 4, None). So I would be unable to distinghuish
between the two.
I don't think it very likely but I could have a table
with indexes from 2147483647 to 2147483700, so having
2147483647 as value that indicated till the end of
the sequence is a bit awkward.
The same problems occur when I have a tree with integer
key values. But even if I don't use integers as keys
I have a problem with what is returned since None is
a valid key and thus it shouldn't be used this way.
--
Antoon Pardon
--
http://mail.python.org/mailman/listinfo/python-list
Re: Problem with slices.
Antoon Pardon wrote:
I'm for the moment writing two classes.
A table, which is like a list, but can start at any integer.
A tree which is like a dictionary, but will iterate over the
keys in sorted order.
The problem is that I would like to implemet slices but, that
seems to be impossible with how slices are implemented now.
I wrote the following class to test things out.
class Tst:
def __getitem__(self, key):
print key
then I called the interpreter and got this:
from tst import Tst
t=Tst()
t[:]
slice(0, 2147483647, None)
t[:9]
slice(0, 9, None)
t[:'ok']
slice(None, 'ok', None)
t['ok':]
slice('ok', None, None)
t[6:]
slice(6, 2147483647, None)
t[1,2]
(1, 2)
t[1,2:]
(1, slice(2, None, None))
t[(1,2):]
slice((1, 2), None, None)
Now suppose tab is a table with indexes from -5 to 12.
tab[:4] would have to make a table ranging from -5 to 4
tab[0:4] would have to make a table ranging from 0 to 4.
But each time I would be given the same argument, being
slice(0, 4, None). So I would be unable to distinghuish
between the two.
I don't think it very likely but I could have a table
with indexes from 2147483647 to 2147483700, so having
2147483647 as value that indicated till the end of
the sequence is a bit awkward.
The same problems occur when I have a tree with integer
key values. But even if I don't use integers as keys
I have a problem with what is returned since None is
a valid key and thus it shouldn't be used this way.
Consider new-style classes:
class T(object):
... def __getitem__(self, key):
... return key
...
t = T()
t[:4]
slice(None, 4, None)
t[0:4]
slice(0, 4, None)
t[0:]
slice(0, None, None)
Peter
--
http://mail.python.org/mailman/listinfo/python-list
