https://configdict.readthedocs.io

$ pip install configdict

A dictionary based on a default prototype. A CheckedDict can only define key:value pairs which are already present in the default. It is possible to define a docstring for each key and different restrictions for the values regarding possible values, ranges and type. A CheckedDict is useful for configuration settings.

Based on CheckedDict, a ConfigDict is a persistent, unique dictionary. It is saved under the config folder determined by the OS and it is updated with each modification. It is useful for implementing configuration of a module / library / app, where there is a default/initial state and the user needs to be able to configure global settings which must be persisted between sessions (similar to the settings in an application)

config = ConfigDict("myproj.subproj")
config.addKey("keyA", 10, doc="documentaion of keyA")
config.addKey("keyB", 0.5, range=(0, 1))
config.addKey("keyC", "blue", choices=("blue", "red"),
              doc="documentation of keyC")
config.load()

Alternatively, a ConfigDict can be created all at once:

config = ConfigDict("myapp",
    default = {
        'font-size': 10.0,
        'font-family': "Monospace",
        'port' : 9100,
    },
    validator = {
        'font-size::range' : (8, 24),
        'port::range' : (9000, 65000),
        'font-family::choices' : {'Roboto', 'Monospace'},
    },
    docs = {
        'port': 'The port number to listen to',
        'font-size': 'The size of the font, in pixels'
    }
)

This will create the dictionary and load any persisted version. Any saved modifications will override the default values. Whenever the user changes any value (via config[key] = newvalue) the dictionary will be saved.

In all other respects a ConfigDict behaves like a normal dictionary.