Entlet inheritance from MutableMapping

[jessica-writes-code]

Question: Should the Entlet class inherit from MutableMapping?

Pro: Formalizes the interface and makes possible future subclassing easier.

Con: Make interact poorly with upcoming changes to .add

[ccbest]

Definitely worth considering. My main concern is that the entlet coerces added values into a list, so from a user perspective the following situation would be a little strange -

>>> entlet['example_field'] = 'test'
>>> entlet['example_field']
['test']