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pprint with compact indent #112632
Description
Feature or enhancement
Proposal:
Add a new parameter to the pprint function that inserts a newline character (\n) after the opening parenthesis, and sets the indent to level * indent. With this parameter, pprint will format nested objects in a manner similar to how formatters like Black or Ruff format them.
>>> t = {'a':2, 'b':{'x':3, 'y':{'t1': 4, 't2':5}}}
>>> pprint(t, indent=4, some_parameter=True)
{
"a": 2,
"b": {
"x": 3,
"y": {
"t1": 4,
"t2": 5
}
}
}With this change, pprint will print in a more width-compact manner, making it easier to read and copy-page pretty printed object to codebase wich follows similar formmating rule.
This feature was hevily inspired by this question on Stackoverflow
Has this already been discussed elsewhere?
No response given
Links to previous discussion of this feature:
No response
Activity
harshit-singhania2000 commented on Mar 10, 2024
Hey! would love to contribute here, can this issue be assigned to me?
stodoran commented on Jan 16, 2025
Any updates on this? I'm left scratching my head wondering why this feature doesn't already exist, I mean the current output for a large nested dictionary with pprint is basically unusable and definitely not pretty, which is a shame because large dictionaries are probably the primary use case for pprint.
If it is a bandwidth thing I'd be happy to try and contribute here if somebody could give me some pointers.
tomasr8 commented on Jan 16, 2025
@stodoran Please, feel free to work on this! You might find the devguide useful: https://devguide.python.org/
As for the implementation itself, you'll probably need to modify the PrettyPrinter class (and more specifically PrettyPrinter._pprint_dict) in Lib/pprint.py. Feel free to ask if you have any questions! :)
StefanTodoran commented on Jan 24, 2025
@tomasr8 I did have two questions
picnixz commented on Jan 24, 2025
I would recommend first opening a DPO thread. There are alternatives such as json.dumps which may not be perfect or 3rd-party packages such as rich (https://rich.readthedocs.io/en/stable/pretty.html).
I don't think pprint was meant to have lots of extensions, as demonstrated by its change history:
The past 10 years have seen small improvements and changes. The same can be said for reprlib:
We should first open a DPO thread before accepting such feature IMO. However, anyone can present a PoC so that we can estimate how complex the addition would be and whether we want to keep it in the standard library or not.
tomasr8 commented on Jan 24, 2025
As a counter point, pprint can already do indents, this is just about adding newlines here and there, so I think the implementation shouldn't be that complex (famous last words 😅 )
picnixz commented on Jan 24, 2025
If it's not that complex, I wouldn't mind skipping the DPO discussion. However it must really be simple! But now I see value in this because:
>>> pprint.pprint(t, indent=4, width=1, compact=0) { 'a': 2, 'b': { 'x': 3, 'y': { 't1': 4, 't2': 5}}}This one is really not a nice way to read stuff.. Maybe we could change the meaning of width or add a balanced=True to make it a balanced output. But I would still be interested in how the implementation eventually looks like.
StefanTodoran commented on Jan 25, 2025
I may have been overthinking it, the solution was not that complex. Here is a basic implementation.
Please let me know how I can improve it, this is my first time contributing. Also, I didn't include a fix for this in my PR but I discovered a bug during testing; pprint throws an error if you try to print a nested Counter inside of another Counter.
gh-112632: Add optional keyword-only argument `expand` to `pprint` (#…
pythongh-112632: Add optional keyword-only argument `expand` to `ppri…
tests: fix test_uses_pprint for Python 3.15 pprint dict
tests: fix test_uses_pprint for Python 3.15 pprint dict
tests: fix test_uses_pprint for Python 3.15 pprint dict