config.py

import json

class Config:
    def __init__(self):
        self._path = None
        self._config = {}

    def open(self, path):
        self._path = path

        try:
            with open(path, "r") as f:
                self._config = json.loads(f.read())
        except FileNotFoundError:
            pass

    def save(self):
        if not self._path:
            return

        data = json.dumps(self._config, indent=4, sort_keys=True)

        with open(self._path, "w") as f:
            f.write(data)

    def get(self, key, default=None):
        d = self._config
        path = key.split("/")

        for entry in path:
            d = d.get(entry)
            if d is None:
                self.set(key, default)
                return default

        return d

    def set(self, key, value):
        d = self._config
        path = key.split("/")

        for i, entry in enumerate(path):
            if i == len(path) - 1:
                d[entry] = value
                break
            if entry not in d:
                d[entry] = {}

            d = d.get(entry)

        self.save()

config = Config()