classification
Title: Improve repr for structseq objects to show named, but unindexed fields
Type: enhancement Stage: patch review
Components: Interpreter Core Versions: Python 3.8
process
Status: open Resolution:
Dependencies: Superseder:
Assigned To: pitrou Nosy List: Arfrever, berker.peksag, dlam, eric.araujo, eric.snow, ezio.melotti, lilydjwg, mblahay, pconnell, pitrou, rhettinger, sunfinite
Priority: low Keywords: easy, patch

Created on 2011-03-27 22:14 by rhettinger, last changed 2019-05-06 18:37 by mblahay.

Files
File name Uploaded Description Edit
issue11698.patch dlam, 2012-07-16 05:18
structseq_2.patch sunfinite, 2013-11-07 12:45 Show named but unindexed fields under the dict keyword argument review
Messages (13)
msg132372 - (view) Author: Raymond Hettinger (rhettinger) * (Python committer) Date: 2011-03-27 22:14
The current __repr__ for structseq only shows the name/value pairs for the positional part and it ignores the other named fields.

For example, os.stat(somefile) returns:
posix.stat_result(st_mode=33277, st_ino=8468407, st_dev=234881026, st_nlink=1, st_uid=0, st_gid=80, st_size=25424, st_atime=1301263901, st_mtime=1298229258, st_ctime=1298283922)

but it doesn't show the other named fields and their values:
{'st_ctime': 1298283922.0, 'st_rdev': 0, 'st_mtime': 1298229258.0, 'st_blocks': 56, 'st_flags': 0, 'st_gen': 0, 'st_atime': 1301263901.0, 'st_blksize': 4096, 'st_birthtime': 1298229258.0}

The __reduce__ method for structseq returns both the tuple portion and the dictionary portion.  The latter needs to be added to the repr so that information doesn't get hidden from the user.
msg153754 - (view) Author: Berker Peksag (berker.peksag) * (Python committer) Date: 2012-02-20 01:55
I'd like to work on this issue. I found the Objects/structseq.c [1] file. Am I on the right path?

Thanks!

[1] http://hg.python.org/cpython/file/5b4b70bd2b6f/Objects/structseq.c#l157
msg153755 - (view) Author: Éric Araujo (eric.araujo) * (Python committer) Date: 2012-02-20 01:56
You are!  See the devguide for more setup guidelines.
msg155261 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2012-03-09 19:49
+1. Also, the repr() should show the float values of st_mtime and friends, rather than truncated integers.
msg165570 - (view) Author: David Lam (dlam) * Date: 2012-07-16 05:18
hi hi,  found this bug after clicking the "Easy issues" link

i basically just took Ray's hint to look at the __reduce__ method, and applied it to the __repr__ method in this patch

also updated is the test_repr() unittest
msg188416 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2013-05-04 22:20
Thanks for the patch. (Yes, I'm looking at this a bit late :-))

First, there seems to be a problem with the repr() of of.stat() results:

 ./python -c "import os; print(os.stat('LICENSE'))"
posix.stat_result(st_mode=33204, st_ino=6553619, st_dev=2053, st_nlink=1, st_uid=1000, st_gid=1000, st_size=15089, st_atime=1367693898, st_mtime=1365264866, st_ctime=1366481591, st_atime=1367693898.528636, st_mtime=1365264866.4163036, st_ctime=1366481591.9862735, st_atime_ns=1367693898528635928, st_mtime_ns=1365264866416303676, st_ctime_ns=1366481591986273627, st_blksize=4096, st_blocks=32, st_rdev=0)

As you see, fields such as "st_atime" are duplicated.

There are other issues with the patch:

* C variable declarations should always be at the beginning of blocks (otherwise it's not C89-compliant)

* C++-style comments (//) are forbidden

* I don't understand in which circumstances `Py_TYPE(obj)->tp_members[i-n_unnamed_fields].name` can be NULL
msg200624 - (view) Author: Sunny K (sunfinite) * Date: 2013-10-20 19:45
Added patch for 3.4.

The patch demarcates the output by adding a {...} around the dictionary portion. Please let me know if this is the right format or if not required at all. It is a simple change.
msg200718 - (view) Author: Antoine Pitrou (pitrou) * (Python committer) Date: 2013-10-21 08:25
Hmm, does anyone have an opinion for or against the proposed representation in Sunny's patch? 

Sunny, if you haven't done so, could you sign a contributor's agreement? http://www.python.org/psf/contrib/
Thanks!
msg202332 - (view) Author: Sunny K (sunfinite) * Date: 2013-11-07 12:45
The previous patch had a wrong mapping between keys and values. The 
current implementation of repr means that duplicated keys will be
present when invisible fields are included. See points 2 and 3 in
http://bugs.python.org/issue1820#msg202330 for more explanation.

I have sidestepped that issue by placing invisible fields under the dict argument. This also plays well with the current code in 
structseq_new and eval(repr(obj)) works.

The output with the patch is:

$./python -c "import os; print(os.stat('LICENSE'))"
os.stat_result(st_mode=33188, st_ino=577299, st_dev=64512, st_nlink=1, st_uid=33616, st_gid=600, st_size=12749, st_atime=1382696747, 
st_mtime=1382361968, st_ctime=1382361968,
dict={'st_atime':1382696747.0, 'st_mtime':1382361968.0,
'st_ctime':1382361968.0, 'st_atime_ns':1382696747000000000, 
'st_mtime_ns':1382361968000000000, 'st_ctime_ns':1382361968000000000, 
'st_blksize':4096, 'st_blocks':32, 'st_rdev':0})
msg202364 - (view) Author: Arfrever Frehtes Taifersar Arahesis (Arfrever) * (Python triager) Date: 2013-11-07 16:44
IMHO '*' could be used as a separator, since relation between indexable fields and named, unindexable fields is similar to relation between positional-or-keyword parameters and keyword-only parameters.

$./python -c "import os; print(os.stat('LICENSE'))"
os.stat_result(st_mode=33188, st_ino=577299, st_dev=64512, st_nlink=1, st_uid=33616, st_gid=600, st_size=12749, st_atime=1382696747, st_mtime=1382361968, st_ctime=1382361968, *, st_atime=1382696747.0, st_mtime=1382361968.0, st_ctime=1382361968.0, st_atime_ns=1382696747000000000, st_mtime_ns=1382361968000000000, st_ctime_ns=1382361968000000000, st_blksize=4096, st_blocks=32, st_rdev=0)
msg224473 - (view) Author: Mark Lawrence (BreamoreBoy) * Date: 2014-08-01 08:30
Could somebody pick this up please as it fixes #5907.
msg341578 - (view) Author: Michael Blahay (mblahay) * Date: 2019-05-06 17:50
I will work on this
msg341591 - (view) Author: Michael Blahay (mblahay) * Date: 2019-05-06 18:37
I have been advised to avoid enhancements like this one, so I am setting this back down. Also, this should be relabeled as easy(c).
History
Date User Action Args
2019-05-06 18:37:50mblahaysetnosy: rhettinger, pitrou, ezio.melotti, eric.araujo, Arfrever, eric.snow, lilydjwg, berker.peksag, dlam, pconnell, sunfinite, mblahay
messages: + msg341591
2019-05-06 17:50:03mblahaysetnosy: + mblahay
messages: + msg341578
2018-01-29 20:52:31rhettingersetversions: + Python 3.8, - Python 3.7
2016-10-03 21:16:12BreamoreBoysetnosy: - BreamoreBoy
2016-10-03 16:18:19belopolskysetstage: patch review
versions: + Python 3.7, - Python 3.4
2015-01-21 08:15:15lilydjwgsetnosy: + lilydjwg
2014-08-01 08:30:28BreamoreBoysetnosy: + BreamoreBoy
messages: + msg224473
2013-11-07 16:44:28Arfreversetmessages: + msg202364
2013-11-07 12:45:28sunfinitesetfiles: + structseq_2.patch

messages: + msg202332
2013-11-07 12:42:36sunfinitesetfiles: - structseq.patch
2013-10-21 08:25:31pitrousetmessages: + msg200718
2013-10-21 05:40:07rhettingersetassignee: pitrou
2013-10-20 19:45:07sunfinitesetfiles: + structseq.patch
nosy: + sunfinite
messages: + msg200624

2013-07-12 07:44:40rhettingersetversions: + Python 3.4, - Python 3.3
2013-06-25 16:42:15eric.snowsetnosy: + eric.snow
2013-05-04 22:20:29pitrousetmessages: + msg188416
2013-04-19 19:30:14pconnellsetnosy: + pconnell
2012-08-23 14:37:27moijes12setnosy: - moijes12
2012-08-23 14:26:17moijes12setnosy: + moijes12
2012-07-16 15:03:12Arfreversetnosy: + Arfrever
2012-07-16 05:18:26dlamsetfiles: + issue11698.patch

nosy: + dlam
messages: + msg165570

keywords: + patch
2012-03-09 19:49:30pitrousetnosy: + pitrou
messages: + msg155261
2012-02-20 03:42:02ezio.melottisetnosy: + ezio.melotti
2012-02-20 01:56:39eric.araujosetmessages: + msg153755
2012-02-20 01:55:05berker.peksagsetnosy: + berker.peksag
messages: + msg153754
2011-07-13 15:41:10eric.araujosetnosy: + eric.araujo
2011-03-27 22:14:56rhettingercreate