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rhettinger opened this issue Dec 2, 2021 · 9 comments
Closed

Teach pprint about dict views #90117

rhettinger opened this issue Dec 2, 2021 · 9 comments
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3.11 only security fixes easy stdlib Python modules in the Lib dir type-feature A feature request or enhancement

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@rhettinger
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BPO 45959
Nosy @rhettinger, @devdanzin, @merwok, @AlexWaygood, @david-peled, @joshinsel
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  • gh-90117: handle dict and mapping views in pprint #30135
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    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 = None
closed_at = None
created_at = <Date 2021-12-02.07:06:56.201>
labels = ['easy', 'type-feature', 'library', '3.11']
title = 'Teach pprint about dict views'
updated_at = <Date 2022-01-18.01:57:55.609>
user = 'https://github.com/rhettinger'

    bugs.python.org fields:

    activity = <Date 2022-01-18.01:57:55.609>
actor = 'eric.araujo'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-12-02.07:06:56.201>
creator = 'rhettinger'
dependencies = []
files = []
hgrepos = []
issue_num = 45959
keywords = ['patch', 'easy']
message_count = 5.0
messages = ['407513', '408582', '408648', '408682', '410839']
nosy_count = 6.0
nosy_names = ['rhettinger', 'ajaksu2', 'eric.araujo', 'AlexWaygood', 'david-peled', 'joshinsel']
pr_nums = ['30135']
priority = 'normal'
resolution = None
stage = 'patch review'
status = 'open'
superseder = None
type = 'enhancement'
url = 'https://bugs.python.org/issue45959'
versions = ['Python 3.11']
    @rhettinger
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    The pprint() code has a number of type or protocol specific handlers but doesn't have one for dict views. So, we don't get pretty printing for the key(), values(), and items():

    d = {i:i for i in range(100)}
pprint(d)             # This is handled correctly
pprint(d.keys())      # Printed on one line
pprint(d.values())    # Printed on one line
pprint(d.items())     # Printed on one line

    @rhettinger rhettinger added 3.11 only security fixes stdlib Python modules in the Lib dir easy type-feature A feature request or enhancement labels Dec 2, 2021
    @joshinsel
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    joshinsel mannequin commented Dec 15, 2021

    According to the documentation for pprint, it is supposed to print objects on a single line if possible. See the second paragraph here: https://docs.python.org/3/library/pprint.html

    @rhettinger
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    More accurate to say that it aspires to print in a single line ONLY if the content fits in the specified width. Otherwise, it prints vertically with appropriate indentation. Indeed, that is the entire purpose of the module; otherwise, we would just use print() which always writes one line.

    @devdanzin
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    Mannequin
    devdanzin mannequin commented Dec 16, 2021

    I have tried to add this. The PR adds:

    • PrettyPrinter._pprint_dict_view to handle dict_keys and dict_values (sorted with _safe_key).
      = PrettyPrinter._pprint_dict_items_view to handle dict_items (sorted using _safe_tuple).
    • Tests.

    Would a NEWS entry or other form of documentation be necessary?

    @merwok
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    merwok commented Jan 18, 2022

    The PR looks good! When the last comments are resolved, unless there is activity from other core devs, I will merge it.

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
    @AbhigyanBose
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    @merwok Hey, what's the situation with the PR for this issue ?

    Is there anything that needs to be done in the PR ?
    If there is, I'm happy to help complete it, or put in a different PR, whichever is required.

    @bedevere-bot bedevere-bot mentioned this issue Mar 4, 2023
    Merged
    @devdanzin
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    Is there anything that needs to be done in the PR ?

    I believe the PR is ready for review.

    @gpshead
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    gpshead commented May 20, 2025

    (we're getting the PR in at the pycon US sprint today)

    gpshead added a commit that referenced this issue May 20, 2025
    @devdanzin @blurb-it
    @merwok @arhadthedev @AA-Turner @gpshead
    gh-90117: handle dict and mapping views in pprint (#30135)
    c7f8e70 
    * Teach pprint about dict views with PrettyPrinter._pprint_dict_view and ._pprint_dict_items_view.
* Use _private names for _dict_*_view attributes of PrettyPrinter.
* Use explicit 'items' keyword when calling _pprint_dict_view from _pprint_dict_items_view.
* 📜🤖 Added by blurb_it.
* Improve tests
* Add tests for collections.abc.[Keys|Items|Mapping|Values]View support in pprint.
* Add support for collections.abc.[Keys|Items|Mapping|Values]View in pprint.
* Split _pprint_dict_view into _pprint_abc_view, so pretty-printing normal dict views and ABC views is handled in two simple methods.
* Simplify redundant code.
* Add collections.abc views to some existing pprint tests.
* Test that views from collection.UserDict are correctly formatted by pprint.
* Handle recursive dict and ABC views.
* Test that subclasses of ABC views work in pprint.
* Test dict views coming from collections.Counter.
* Test ABC views coming from collections.ChainMap.
* Test odict views coming from collections.OrderedDict.
* Rename _pprint_abc_view to _pprint_mapping_abc_view.
* Add pprint test for mapping ABC views where ._mapping has a custom __repr__ and fix ChainMap test.
* When a mapping ABC view has a ._mapping that defines a custom __repr__, dispatch pretty-printing it by that __repr__.
* Add tests for ABC mapping views subclasses that don't replace __repr__, also handling those that delete ._mapping on instances.
* Simplify the pretty printing of ABC mapping views.
* Add a test for depth handling when pretty printing dict views.
* Fix checking whether the view type is a subclass of an items view, add a test.
* Move construction of the views __repr__ set out of _safe_repr.

---------

Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Éric <merwok@netwok.org>
Co-authored-by: Oleg Iarygin <oleg@arhadthedev.net>
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
Co-authored-by: Gregory P. Smith <greg@krypto.org>
    @gpshead
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    gpshead commented May 20, 2025

    Thanks for the contribution! Finally merged. 😁

    @gpshead gpshead closed this as completed May 20, 2025
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