Could set_pointer create structures if it can't find any?

>>> data = {}
>>> set_pointer(data, "/cat/name", "whiskers")
Traceback (most recent call last):
  File "......./jsonpointer.py", line 276, in walk
    return doc[part]
KeyError: 'cat'

During handling of the above exception, another exception occurred:

..........
    raise JsonPointerException("member '%s' not found in %s" % (part, doc))
jsonpointer.JsonPointerException: member 'cat' not found in {}

Could there be an option (off by default) to create dicts/lists as it tries to set things? So instead you'd get:

>>> data = {}
>>> set_pointer(data, "/cat/name", "whiskers", option=True)
{'cat': {'name': 'whiskers'}}

I started hacking on something at https://github.com/stefankoegl/python-json-pointer/compare/master...odscjames:set-create-structures?expand=1

More needs to be done on that, but if I can get something to work is this something your interested in?

I can see there might always be some edge cases around things like creating lists, and I don't think that could be fixed but it might still be useful?

[SquareByte]

NB: The spec would allow that, but it is not required

For example, some applications might stop pointer processing upon an error, while others may attempt to recover from missing values by inserting default ones.

[alb3rtom]

>>> from jsonpointer import set_pointer
>>> obj = {'cities': {}}
>>> set_pointer(obj, '/cities/NewYork', '0')
>>> print(obj)
'cities': {'NewYork': '0'}}

>>> set_pointer(obj, '/cities/LosAngeles/population', '4mln')
>>> print(obj)
---------------------------------------------------------------------------
KeyError: 'LosAngeles'
...
JsonPointerException("member '%s' not found in %s" % (part, doc))
JsonPointerException: member 'LosAngeles' not found in {'NewYork': '0'}

@odscjames, currently it is possible to set a single missing level works, but it is not possible to go deeper. I think it might be useful to implement this feature recursively.