How?

Objdiff uses difflib built into python for lists and tuples (basically sorted things) and implements its own comparison code for dictionaries. User types are detected via the collections.abc.Mapping type and instance comparison and are treated as dictionaries (ie unsorted item => value mappings)

What does this look like?

>>> import objdiff
>>> a = {'a': 1, 'b':[1,2,3], 'c':None}
>>> b = {'a': 1, 'b':[1,4], 'c':'hello'}
>>> objdiff.obj_diff(a, b)
<generator object obj_diff at 0xb6a3da80>

We return an iterator and make use of yield from so you can process large trees of objects efficiently and incremental

>>> from pprint import pprint
>>> pprint(list(objdiff.obj_diff(a, b)))
[modified(path=['c'], old=None, new='hello'),
 modified(path=['b'], old=[1, 2, 3], new=[1, 4]),
 equal(path=['a'], old=1, new=1)]

Expanding out the generator we get back a bunch of tuples containing the command value, key path, before and after value

>>> c = {'a':{1: None, 2: 2, 3: 3}, 'b': None}
>>> d = {'a':{1: 1, 2: 2}, 'b': {'1':{}, '2':{'2':2}}}
>>> pprint(list(objdiff.obj_diff(c, d)))
[modified(path=['b'], old=None, new={'1': {}, '2': {'2': 2}}),
 modified(path=['a', 1], old=None, new=1),
 equal(path=['a', 2], old=2, new=2),
 deleted(path=['a', 3], val=3)]

Note: in the above how you get a full list of keys to the destined object after the command value.

In total there are 4 types of command, as listed below with one internal type that can be ignored.

• added

• deleted

• modified

• equal (internal, scalar values are equal)

More documentation can be found at Blitz works docs

Changelog