json_dispatch.py

from functools import singledispatch
from collections import Iterable
from json import JSONEncoder, dumps

json_converter = singledispatch(JSONEncoder().default)

json_converter.register(Iterable)(list)

class A:
    def __init__(self, a, b):
        self.a = a
        self.b = b

@json_converter.register(A)
def _(a):
    return a.__dict__

print(dumps([{1}], default=json_converter))
print(dumps([A(1,2)], default=json_converter))

# I tried to use this to get a generic and extensible way to serialize stuff to json, but when plugging this inside a JSONEncoder subclass for use with a Flask app, the encoder was apparently ignored :/