Nested dictionaries

nested_dict.py

"""
The "ddict" is able to create nested structures. With the help of "defaultdict",
it creates arbitrary levels of "dict"-like objects. 

Run the doctests with:

$ python3 -m doctest nested_dict.py


>>> d = ddict(a=ddict(b=ddict(c=10)) )
>>> d["a"]["b"]["c"]
10
>>> d["a"]["b"]["d"] == {}
True
>>> d["a"]["b"]["d"] = 42
>>> d["a"]["b"]["d"]
42
>>> d["foo"]["bar"]["baz"] == {}
True
>>> d1 = ddict({"a": {"b": {"c": 10} } })
>>> d2 = ddict()
>>> d2["a"]["b"]["c"] = 10
>>> d1 == d2
True

# See also
https://docs.python.org/3/library/collections.html#defaultdict-objects
https://stackoverflow.com/a/19189356
"""

from collections import defaultdict
from functools import partial


def ddict(*args, **kwargs):
    """A dict for nested structures."""
    def _default(*def_args, **def_kwargs):
       return defaultdict(_default, *def_args, **def_kwargs)
    thedict = partial(defaultdict, _default)
    return thedict(*args, **kwargs)


if __name__ == "__main__":
    d1 = ddict({"a": {"b": {"c": 10} } })
    d2 = ddict()
    d2["a"]["b"]["c"] = 10
    assert d1 == d2
    print(d1)