printobject 0.1.3

Generic pretty printer of python objects

Python version support: CPython 2.6, 2.7, 3.2, 3.3 and PyPy.

Installation

$ pip install printobject

Usage

The standard library pprint module is great at visualizing all kinds of built-in types like lists, dicts and tuples. But it does not attempt to introspect user defined types. This is where printobject comes in. It dumps the internals of any object as a dict, and pretty prints using pprint.

Key points:

• Any type of object can printed, but depending on the type the output will be more or less insightful.

• Object introspection is based on the use of dir rather than __dict__ directly.

• Object attributes only include attributes owned by the object, omitting class attributes.

• Callables are omitted when introspecting objects. The goal is to visualize the data in objects.

• The synthetic attributes ___name___ and ___type___ (yes, that’s three underscores!!!) are included in order to provide some metadata about the object being printed.

Modules

This modules defines a number of test_xxx functions at module level. They are included in a tests list and visible in the output, but not listed at top level because they are callables.

>>> import sys
>>> from printobject import pp
>>> pp(sys.modules[__name__])
{'___name___': '__main__',
 '___type___': '<module {id0}>',
 '__builtins__': <module 'builtins' (built-in)>,
 '__cached__': None,
 '__file__': '/home/user/code/printobject/printobject/demos.py',
 '__loader__': <_frozen_importlib.SourceFileLoader object at 0xb71c520c>,
 '__name__': '__main__',
 '__package__': 'printobject',
 'absolute_import': _Feature((2, 5, 0, 'alpha', 1), (3, 0, 0, 'alpha', 0), 16384),
 'defaults': ('Module',),
 're': <module 're' from '/home/user/code/printobject/.tox/py33/lib/python3.3/re.py'>,
 'sys': <module 'sys' (built-in)>,
 'tests': [<function test_module at 0xb72d23d4>,
           <function test_class at 0xb71c60bc>,
           <function test_instance at 0xb71c6104>,
           <function test_instance_collapsed at 0xb71c614c>,
           <function test_class_old at 0xb71c6194>,
           <function test_instance_old at 0xb71c61dc>,
           <function test_instance_old_collapsed at 0xb71c6224>,
           <function test_function at 0xb71c626c>,
           <function test_method at 0xb71c62b4>,
           <function test_lambda at 0xb71c62fc>,
           <function test_iterable at 0xb71c6344>,
           <function test_generator at 0xb71c638c>]}

Classes

>>> class Node(object):
>>>     classatt = 'hidden'
>>>     def __init__(self, name):
>>>         self.name = name

>>> from printobject import pp
>>> pp(Node)

{'___name___': 'Node',
 '___type___': '<type {id0}>',
 '__weakref__': {'___name___': '__weakref__',
                 '___type___': '<getset_descriptor {id1}>'},
 'classatt': "'hidden'"}

Instances

>>> a, b, c, d = Node('A'), Node('B'), Node('C'), Node('D')
>>> a.refs = [b, d]
>>> b.refs = [c]
>>> c.refs = [a]
>>> d.refs = [c]

>>> from printobject import pp
>>> pp(a)

>>> {'___type___': '<Node {id0}>',
>>>  'name': "'A'",
>>>  'refs': [{'___type___': '<Node {id1}>',
>>>            'name': "'B'",
>>>            'refs': [{'___type___': '<Node {id2}>',
>>>                      'name': "'C'",
>>>                      'refs': ['dup <Node {id0}>']}]},
>>>           {'___type___': '<Node {id3}>',
>>>            'name': "'D'",
>>>            'refs': [{'___type___': '<Node {id2}>',
>>>                      'name': "'C'",
>>>                      'refs': ['dup <Node {id0}>']}]}]}