Python 3.x: alternative pprint implementation

Question

Standard pprint module is nice when deals with lists, dicts and so on. But sometimes completely unusable with custom classes:

The only way to make it print usable information about an object of some class is to override __repr__, but what if my class already have nice, eval()'able __repr__ which is not showing the information I want to see in pprint ouput?
Ok, I will write print-oriented __repr__, but in this case it is impossible to pretty-print something inside my class:

.

class Data:
    def __init__(self):
        self.d = {...}

I can't pretty-print self.d contents, I can return one-line representation only(at least without playing with stacktraces, etc). - Overriding PrettyPrinter is not an option, I dont want to do it every time I want to pretty-print the same class.

So... Is there any alternatives to pprint which allows to make a custom class pretty-printable?

Found https://pypi.python.org/pypi/pretty/0.1 , but it seems to be py2.X only — Equidamoid, May 19 '13 at 10:25
"I can return one-line representation only" -- why is this? NumPy for example returns multi-line repr()s that work just fine. Here's an example, as a Python string : `"array([(0, 0, (0, 0, 0)), (0, 0, (0, 0, 0)), (0, 0, (0, 0, 0)),\n (0, 0, (0, 0, 0))], \n dtype=[('foo', 'u1'), ('bar', ' — kampu, May 19 '13 at 10:31
@kampu I meant I cant return multiline string because it will break `pprint` indentation. — Equidamoid, May 19 '13 at 10:55
Yeah, I tried to edit and indicate I'd just realized that, but the 5min grace period on editing had run out. Good to know we're on the same page, anyway :) — kampu, May 19 '13 at 10:58
@Equidamoid, if you need a Python 3 solution, please indicate it in your question, and add an appropriate tag. — utapyngo, May 19 '13 at 15:12
And why is it impossible to pretty-print something inside your class in case of writing a custom `__repr__`? The string it returns can contain a representation of any field of your object. — utapyngo, May 19 '13 at 15:29
@utapyngo done. Oops, the phrase about subclassing is incorrect a little bit %) I just don't want to add support for the particular class to `PrettyPrinter` (because class-specific code shouldn't be there), and looking for "generic" solution, such as the one mentioned in my 1st comment. — Equidamoid, May 19 '13 at 15:43
@utapyngo it is impossible to generate proper multiline string in `__repr__` because of unknown current indentation level. — Equidamoid, May 19 '13 at 21:23

score 4 · Accepted Answer · edited Dec 06 '19 at 15:26

4

There is an improved and maintained Python 2.x/3.x port of "pretty" library in IPython: https://ipython.readthedocs.io/en/stable/api/generated/IPython.lib.pretty.html

edited Dec 06 '19 at 15:26

snoob dogg

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answered Sep 08 '13 at 12:31

Mikhail Korobov

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score 3 · Answer 2 · answered May 19 '13 at 15:49

3

If the pretty module satisfies your needs, you can make it work with Python 3.

Download and unpack the pretty.py file.
Run 2to3 on it:
```
python -m lib2to3 -w pretty.py
```

Comment out the following lines:

569: types.DictProxyType:        _dict_pprinter_factory('<dictproxy {', '}>'),
580: xrange:                     _repr_pprint,

Put the file near your script.
Import it as usual:
```
import pretty
```

answered May 19 '13 at 15:49

utapyngo

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@Equidamoid: have you succeeded? – utapyngo May 22 '13 at 11:51
However, `pretty` doesn't like numpy.ndarray =( – Equidamoid May 25 '13 at 10:21

score 1 · Answer 3 · answered May 19 '13 at 12:01

1

for pretty printing you may be looking for __str__ instead of (or as well as) __repr__

e.g.

>>> import datetime
>>> now = datetime.datetime.now()
>>> print now
2013-05-19 13:00:34.085383
>>> print repr(now)
datetime.datetime(2013, 5, 19, 13, 0, 34, 85383)

answered May 19 '13 at 12:01

second

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Now imagine that instead of datetime you have a class with several `dict`s big enough so they don't fit into one terminal row. And then you have a `dict` with several those objects... That's my case. – Equidamoid May 19 '13 at 21:26

score 0 · Answer 4 · answered May 19 '13 at 16:08

0

You can create a generic solution that prints the contents of object fields by subclassing PrettyPrinter. obj.__dict__ will give you a dictionary of all fields of obj.

Or you can just use obj.__class__.__name__ + pformat(obj.__dict__).

answered May 19 '13 at 16:08

utapyngo

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Python 3.x: alternative pprint implementation

4 Answers4