pprint doesn't use all width

[serhiy-storchaka]

BPO	19105
Nosy	@freddrake, @pitrou, @serhiy-storchaka
Files	pprint_all_width.patch pprint_all_width_2.patch pprint_all_width_3.patch

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/serhiy-storchaka'
closed_at = <Date 2015-02-14.14:09:23.510>
created_at = <Date 2013-09-27.13:50:34.595>
labels = ['type-feature', 'library']
title = "pprint doesn't use all width"
updated_at = <Date 2015-04-05.05:24:43.198>
user = 'https://github.com/serhiy-storchaka'

bugs.python.org fields:

activity = <Date 2015-04-05.05:24:43.198>
actor = 'python-dev'
assignee = 'serhiy.storchaka'
closed = True
closed_date = <Date 2015-02-14.14:09:23.510>
closer = 'serhiy.storchaka'
components = ['Library (Lib)']
creation = <Date 2013-09-27.13:50:34.595>
creator = 'serhiy.storchaka'
dependencies = []
files = ['31945', '37308', '37517']
hgrepos = []
issue_num = 19105
keywords = ['patch', 'needs review']
message_count = 7.0
messages = ['198475', '198851', '231656', '231824', '232982', '235954', '240104']
nosy_count = 4.0
nosy_names = ['fdrake', 'pitrou', 'python-dev', 'serhiy.storchaka']
pr_nums = []
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue19105'
versions = ['Python 3.5']

[serhiy-storchaka]

pprint not only adds indentation, but also increases right margin for nested items.

>>> pprint.pprint([' '.join(str(i) for i in range(30))]*2)
['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 '
 '28 29',
 '0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 '
 '28 29']
>>> pprint.pprint([[[[[[[[[[[[' '.join(str(i) for i in range(30))]]]]]]]]]]]]*2)
[[[[[[[[[[[['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 '
            '21 22 23 24 25 26 27 28 29']]]]]]]]]]],
 [[[[[[[[[[['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 '
            '21 22 23 24 25 26 27 28 29']]]]]]]]]]]]

As you can see in second example there is a place for at least '21 22 23 ' at the right. In case of multiline representation of nested items pprint can reserve space only at the end of last line and continue inner lines to full width.

[serhiy-storchaka]

Here is a patch.

Without patch:

>>> pprint.pprint([[[[[[[[[[0, 0, 0]]*3]]]]]]]], width=21)
[[[[[[[[[[0,
          0,
          0],
         [0,
          0,
          0],
         [0,
          0,
          0]]]]]]]]]]

With patch:

>>> pprint.pprint([[[[[[[[[[0, 0, 0]]*3]]]]]]]], width=21)
[[[[[[[[[[0, 0, 0],
         [0, 0, 0],
         [0,
          0,
          0]]]]]]]]]]

[serhiy-storchaka]

Could anyone please make a review?

[serhiy-storchaka]

Thank you Antoine for your review.

But first variant of the patch doesn't affect an example at the top of this issue, it doesn't change string formatting. The second variant makes string formatting use all free space at the right. With the patch:

>> import pprint
>> print('='*80) # a rule
================================================================================

>>> pprint.pprint([' '.join(str(i) for i in range(30))]*2)
['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 '
 '29',
 '0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 '
 '29']
>>> pprint.pprint([[[[[[[[[[[[' '.join(str(i) for i in range(30))]]]]]]]]]]]]*2)
[[[[[[[[[[[['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 '
            '25 26 27 28 29']]]]]]]]]]],
 [[[[[[[[[[['0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 '
            '25 26 27 28 29']]]]]]]]]]]]

Could you please make a review of new patch?

[serhiy-storchaka]

Resolved conflicts with bpo-19104.

[python-dev]

New changeset 7a6671d491da by Serhiy Storchaka in branch 'default':
Issue bpo-19105: pprint now more efficiently uses free space at the right.
https://hg.python.org/cpython/rev/7a6671d491da

[python-dev]

New changeset 6d9520e2223f by Serhiy Storchaka in branch 'default':
Updated pprint examples in according to issue bpo-19105.
https://hg.python.org/cpython/rev/6d9520e2223f