start from 3.6+, dict keys are ordered heir creation order.
the builtin print function works as we expected, but for 
pprint, the keys is sorted. should we using the sorted version
or just obey the creation order as builtin print?

Until dict insertion order is guaranteed, it doesn't make sense to change pprint().

Concur with Raymond.

If/when order is guaranteed (3.7?) we should have a pprint that respects current order, 

-or-

we should get an improved pprint (maybe named pp or print?) that understands mappings and other abstract data types.

I had a conversation about pprint at the Python meetup last night. It kinda went like this: https://www.youtube.com/watch?v=NpYEJx7PkWE 

Maybe now's the time for improved behavior?

A year ago I proposed to add a method for detecting whether a dict preserves an order and in what sense. [1] But this idea was rejected.

[1] https://mail.python.org/pipermail/python-dev/2016-October/146597.html

IMHO since Guido said that dictionary order is guaranteed going forward [1], the order should now be preserved in 3.6+ 

Getting a sorted pprint'ed dict in a Py3.6.1 was a surprise to me coming from Python2.

The default ordered dict is to me the killer feature of 3 and a major driver to migrate from 2.

[1] https://mail.python.org/pipermail/python-dev/2017-December/151286.html

@terry.reedy - If I understand correctly, this issue was closed by you awaiting what would happen with the dict insertion order after 3.6.

It has been decided that dict insertion will stay for now and in the future. >>> Should this issue now be reopened?

And I would favor backward compatibility (key sort order) with an additional keyword for pprint to display it "unsorted" order (from pprint perspective, insertion order for dicts and OrderedDicts, and whatever other order for whatever other dicts).

Please reopen this.
With version 3.7 and guaranteed dict order pprint should not sort by key.

I reopened this issue, and change affected versions to 3.6, 3.7 and 3.8.

Hi josephsmeng, dict order preservation is now used in a lot of place in Python. I will post a patch to make pprint use insertion order in a few hours.

https://docs.python.org/3/library/pprint.html

> Dictionaries are sorted by key before the display is computed.

https://mail.python.org/pipermail/python-dev/2017-December/151369.html . There was some discussion in the thread about this being a breaking change and the behavior of pprint. @remi.lapeyre I would suggest waiting for a core dev on approving this change before proceeding with a patch to avoid work being wasted.

If you stop sorting keys in pprint, then unittest.TestCase.assertDictEquals() (and pytest and such) won't be able to generate a meaningful diff when 2 dicts aren't equal, and it will be much more complicated to understand why a test fails.

https://github.com/python/cpython/blob/89427cd0feae25bbc8693abdccfa6a8c81a2689c/Lib/unittest/case.py#L1172-L1175

(well except if we fix unittest, but then external test runners will need fixing too, and it might not be the only place diff is used on the result of pprint to see how two objects differ)

Consider adding a flag to switch between sorted order and insertion order (defaulting to the current behavior).  For convenience, add a short-cut function to call pprint() with the flag set to False.

    def pprint(data, *, sort_dicts=True):
        ...

    def pp(data, *args, **kwds):
        pprint(data, *args, sort_dicts=False, **kwds)

Hi!

>    def pprint(data, *, sort_dicts=True):
>        ...

>    def pp(data, *args, **kwds):
>        pprint(data, *args, sort_dicts=False, **kwds)

We could use the parameters `sort=`? IMHO is better a short parameters name.

If we assign by default sort_dicts=True, that would have some error on unittest, isn't?

pprint only sorts dicts currently so sort_dicts is better than sort that sounds more general. sort_dicts=True is the current behavior so I guess this is backwards compatible way to do this change.

> pprint only sorts dicts currently so sort_dicts is better than sort that sounds more general. 

Yes. Because pprint just sort dicts, I think that is better rename the parameter like just sort. But was an opinion, that does not affect to the behavior. 

> sort_dicts=True is the current behavior so I guess this is backwards compatible way to do this change.

I understand it. I was confuse.

I agree with Karthikeyan, I would expect sort=True to sort all collections, including tuples and lists for example.

New changeset 96831c7fcf888af187bbae8254608cccb4d6a03c by Raymond Hettinger (Rémi Lapeyre) in branch 'master':
bpo-30670: Add pp function to the pprint module (GH-11769)
https://github.com/python/cpython/commit/96831c7fcf888af187bbae8254608cccb4d6a03c

Thanks for the contribution.