[Patches] [ python-Patches-1617699 ] slice-object support for ctypes Pointer/Array

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Patches item #1617699, was opened at 2006-12-18 05:28
Message generated for change (Comment added) made by theller
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Category: Modules
Group: Python 2.6
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Thomas Wouters (twouters)
Assigned to: Thomas Heller (theller)
Summary: slice-object support for ctypes Pointer/Array

Initial Comment:
Support for slicing ctypes' Pointer and Array types with slice objects, although only for step=1 case.
(Backported from p3yk-noslice branch.)


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>Comment By: Thomas Heller (theller)
Date: 2007-07-12 12:17

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I think that full slicing support for pointers/arrays would be great. 
Presonally I have a use case for step = -1, in other words, I need to
iterate backwards over a ctypes array.

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Comment By: Thomas Wouters (twouters)
Date: 2007-07-12 09:54

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Thomas, do you consider non-step-1 slicing important? I'd really like to
get the noslice branch merged into p3yk soon-ish, and I need to know which
bits I need to commit to the trunk first (to avoid merge conflicts for the
rest of the lifetime of the 2.x codebase.)

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Comment By: Thomas Wouters (twouters)
Date: 2007-01-15 12:48

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The point is that simple slicing will go away, and extended slices (with
sliceobjects) are used in various places, and currently can't be passed on
to ctypes arrays and pointers. That is to say, a Python class defining
__getitem__ but not __getslice__ still supports slice syntax, but it can't
do 'pointer[sliceobj]' -- it would have to do
'pointer[sliceobj.start:sliceobj.end]'. Also, because simple slices will go
away, this code will have to be added to the p3yk branch in any case;
having it in the trunk just makes for easier maintenance.

Oh, and the non-support for steps other than 1 is not a fundamental issue,
I just couldn't bear to write the code for that if you didn't think it
would be useful, as I'd already written the same logic and arithmetic for
array, tupleseq, mmap and I forget what else :P You can consider this code
half-done, if you wish; I'll get to it again soon enough.

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Comment By: Thomas Heller (theller)
Date: 2007-01-12 21:48

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Thomas, a question:  Since steps != 1 are not supported, does this patch
have any value?
IIUC, array[x:y] returns exactly the same as array[x:y:1] for all x and y
values.

Formally, the patch is missing unittests and documentation ;-).

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Comment By: Thomas Heller (theller)
Date: 2006-12-20 19:45

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Unfortunately I'm unable to review or work on this patch *this year*.  I
will definitely take a look in January.  Sorry.

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