[issue5191] Partial function application 'from the right'
New submission from Ben North :
The functools module includes a 'partial' class, which allows partial
function application either by positional arguments or keyword
arguments. However, it cannot be used to create, for example, a
function splitting a string on commas, or a function to extracts logs to
base 10. I posted
http://mail.python.org/pipermail/python-dev/2009-January/085638.html
which suggested a 'partial_right' feature, such that the following would
work:
>>> import functools, math
>>> split_comma = functools.partial_right(str.split, ',')
>>> split_comma('a,b,c')
['a', 'b', 'c']
>>> log_10 = functools.partial_right(math.log, 10.0)
>>> log_10(100.0)
2.0
There was some useful discussion, but generally the feeling was that the
extra complexity outweighed the potential benefits. Also, chained
partial applications were troublesome.
The overlap in functionality between 'partial_right' and an existing
patch (#1706256) to allow skipping of positional arguments was raised.
I think the present issue should probably be closed/rejected, but it was
suggested on the mailing list that having the issue and patch on the
record might be useful. Patches are against 2.6.1 source.
--
messages: 81457
nosy: bennorth
severity: normal
status: open
title: Partial function application 'from the right'
type: feature request
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[issue5191] Partial function application 'from the right'
Changes by Ben North : -- keywords: +patch Added file: http://bugs.python.org/file12991/_functoolsmodule.patch ___ Python tracker <http://bugs.python.org/issue5191> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5191] Partial function application 'from the right'
Changes by Ben North : Added file: http://bugs.python.org/file12992/test_functools.patch ___ Python tracker <http://bugs.python.org/issue5191> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Change by Ben North : -- pull_requests: +5203 stage: needs patch -> patch review ___ Python tracker <https://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment: Terry in msg310785: > As I expected from the fact that Ben once did a separate 2.7 > version, the auto backport for 2.7 failed. Ben, since you know what > code changes are needed, can you prepare a backport (cherry pick) > PR? Yes, that's right, there were some differences between the approaches in Py2 and Py3. I've created PR5357 for the 2.7 backport. -- ___ Python tracker <https://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment: PR4823 created as per msg308086. -- ___ Python tracker <https://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue32137] Stack overflow in repr of deeply nested dicts
Change by Ben North : -- pull_requests: +4716 ___ Python tracker <https://bugs.python.org/issue32137> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
New submission from Ben North:
#18019 noted the following crash in earlier 2.7:
>>> d={}
>>> d[42]=d.viewvalues()
>>> d
This issue has been fixed; the behaviour now is that a RuntimeError is
produced for a recursive dictionary view:
>>> d={}
>>> d[42]=d.viewvalues()
>>> d # (output line-broken:)
{42: Traceback (most recent call last):
File "", line 1, in
RuntimeError: maximum recursion depth exceeded
while getting the repr of a list
Before finding this, though, I'd investigated and made a patch which
produces a similar "..." output to a recursive dictionary. Reworking
against current 2.7, the behaviour would be:
>>> x={}
>>> x[42]=x
>>> x # existing behaviour for dictionaries:
{42: {...}}
>>> d={}
>>> d[42]=d.viewvalues()
>>> d # new behaviour:
{42: dict_values([...])}
>>> d[43]=d.viewitems()
>>> d # (output line-broken:)
{42: dict_values([..., dict_items([(42, ...), (43, ...)])]),
43: dict_items([(42, dict_values([..., ...])), (43, ...)])}
Attached is the patch, against current 2.7 branch. If there is interest
in applying this, I will create a proper patch (changelog entry, fix to
Lib/test/test_dictviews.py, etc.).
On python-dev, Gregory Smith noted:
Given that the RuntimeError fix has been released, your proposed
... behavior is arguably a new feature so I'd only expect this to
make sense for consideration in 3.4, not 2.7. (if accepted at all)
[http://mail.python.org/pipermail/python-dev/2013-July/127489.html]
so I have marked for consideration for versions 2.7 and 3.4.
--
components: Interpreter Core
files: non-error-recursive-dictview.patch
keywords: patch
messages: 193570
nosy: bennorth
priority: normal
severity: normal
status: open
title: Avoid error from repr() of recursive dictview
type: behavior
versions: Python 2.7, Python 3.4
Added file: http://bugs.python.org/file31019/non-error-recursive-dictview.patch
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[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment:
New patch including tests attached, against 3.3. Terry Reedy's example
above now gives
>>> d = {}
>>> d[1] = d.keys()
>>> d[2] = d.values()
>>> d
{1: dict_keys([1, 2]), 2: dict_values([dict_keys([1, 2]), ...])}
which I think is preferable.
Summary of patch:
dictobject.c:
dictview_repr() now uses a Py_ReprEnter() / Py_ReprLeave() pair to
check for recursion, and produces "..." if so. I think I've got the
behaviour correct in the case that PySequence_List() fails, but
couldn't find a way to trigger this in testing.
test_dictviews.py:
test_recursive_repr() checks for the correct string (containing
"...") rather than a RuntimeError.
test_deeply_nested_repr() is a new function, aiming to replace the
original test_recursive_repr(). It checks that a RuntimeError is
raised in the case of a non-recursive but deeply nested structure.
Under --with-pydebug,
./python -m test.regrtest -R20:30 test_dictviews
passes.
--
Added file:
http://bugs.python.org/file31022/non-error-recursive-dictview-3.3.patch
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[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment: New patch, fixing nit noted in msg193624: non-error-recursive-dictview-3.3-1.patch Otherwise same as previous non-error-recursive-dictview-3.3.patch -- Added file: http://bugs.python.org/file31025/non-error-recursive-dictview-3.3-1.patch ___ Python tracker <http://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Changes by Ben North : Added file: http://bugs.python.org/file31089/against-9bf89c909bd4-3.3-1.patch ___ Python tracker <http://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment: I'll attach fresh patches, one against latest 2.7 and one against latest 3.3 (unchanged apart from headers from previous patch). Both branches pass ./python -m test.regrtest -R20:30 test_dictviews -- ___ Python tracker <http://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Changes by Ben North : Added file: http://bugs.python.org/file31088/against-6e1dd1ce95b8-2.7-1.patch ___ Python tracker <http://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue18533] Avoid error from repr() of recursive dictview
Ben North added the comment: Is anything further needed from me before this can be reviewed? -- ___ Python tracker <http://bugs.python.org/issue18533> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5821] Documentation: mention 'close' and iteration for tarfile.TarFile.extractfile()
New submission from Ben North : The current documentation for tarfile.TarFile.extractfile() does not mention that the returned 'file-like object' supports close() and also iteration. The attached patch (against svn trunk) fixes this. (Background: I was wondering whether I could write def process_and_close_file(f_in): with closing(f_in) as f: # Do stuff with f. and have it work whether f_in was a true file or the return value of extractfile(), and thought from the documentation that I couldn't. Of course, I could have just tried it, but I think fixing the documentation wouldn't hurt.) -- assignee: georg.brandl components: Documentation files: tarfile.rst.patch keywords: patch messages: 86366 nosy: bennorth, georg.brandl severity: normal status: open title: Documentation: mention 'close' and iteration for tarfile.TarFile.extractfile() type: feature request Added file: http://bugs.python.org/file13749/tarfile.rst.patch ___ Python tracker <http://bugs.python.org/issue5821> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
