Simple pickling example with a dispatchtable

pickle_with_dispatch.py

import copyreg
import pickle

class Foo(object):
    def __init__(self, bars):
        self.bars = bars

    def __str__(self):
        return 'foo(%s)'%', '.join(['%s(%s)'%(type(b).__name__, b) for b in self.bars])

class Bar(object):
    def __init__(self, v):
        self.v = v

    def __str__(self):
        return f'{self.v}'

    @classmethod
    def pickle(cls, b):
        return SBar, (f'b{b.v}',)

class SBar(object):
    def __init__(self, s):
        self.s = s

    def __str__(self):
        return self.s

foo = Foo([Bar(1), Bar(2)])

with open(r'/tmp/data.pkl', 'wb') as f:
    p = pickle.Pickler(f)
    p.dispatch_table = copyreg.dispatch_table.copy()
    p.dispatch_table[Bar] = Bar.pickle
    print("Pickling ", foo)
    p.dump(foo)

with open(r'/tmp/data.pkl', 'rb') as f:
    data = pickle.load(f)
    print("Loaded: ", data)