What is more pythonic - subclassing dict or creating external functions to manipulate them?

Question

Say I have a dictionary that contains complex classes that need to be loaded and unloaded in a special way. (Not especially special, just outside the bounds of this question.) Should I gracefully subclass the built-in dict like this:

class ExampleClass(dict):
    def __str__(self):
        return 'ExampleClass; '+dict.__str__(self)

    @classmethod
    def loads(cls, string):
        <load object from string here>

    def dumps(self):
        <dump object here>

Or do something like this:

def load_special_structure(string):
    <load object from code here>

def dump_special_structure(obj):
    <dump object here>

That's all the extra functionality I need. It's not too pythonic to have to use a special imported method to dump and load it, but subclassing a dictionary isn't either. On the usage perspective, being able to import that class, load it from a string and use it like a dictionary is really useful.

Answer 1

In general, in Python I favor using functions over subclassing internal classes. In the end, if you write your String -> dict method, you end up working with a dict, pure as the driven snow. Just put your functions in a sensible module and import them only where needed; this will also encourage you not to import the functions everywhere, which will help you out by keeping the IO separated from your logic.