A little object system written in Python, inspired by https://www.aosabook.org/en/500L/a-simple-object-model.html

objects.py

class Type:
    def __init__(self, name, *, method_table=None, parent=None):
        self.name = name
        self.method_table = method_table or {}
        self.parent = parent

    def resolve_method(self, name, /):
        if name in self.method_table:
            return self.method_table[name]
        elif self.parent is not None:
            return self.parent.resolve_method(name)
        return None


TYPE = Type('type')


class Method:
    def __init__(self, function, /):
        self.function = function

    def call(self, instance, /, args, kwargs):
        return self.function(instance, *args, **kwargs)


method = Method


@method
def typeof(instance):
    return instance.base.name


Object = Type('Object', method_table={'typeof': typeof}, parent=TYPE)


class Instance:
    def __init__(self, base, args=(), kwargs=None):
        kwargs = kwargs or {}
        self.base = base
        self.fields = {}

        if init := self.base.resolve_method('__init__'):
            init.call(self, args, kwargs)

    def call_method(self, name, /, args=(), kwargs=None):
        kwargs = kwargs or {}
        if method := self.base.resolve_method(name):
            return method.call(self, args, kwargs)
        raise AttributeError(name)

    def getattr(self, name, /):
        if name in self.fields:
            return self.fields[name]
        raise AttributeError(name)

    def setattr(self, name, value, /):
        self.fields[name] = value

    def delattr(self, name):
        if name in self.fields:
            del self.fields[name]
            return True
        return False


@method
def get_name(self):
    return self.getattr('name')


@method
def set_name(self, name, /):
    return self.setattr('name', name)


@method
def Test_init(self, name):
    self.setattr('name', name)


Test = Type('Test', method_table={
    'get_name': get_name,
    'set_name': set_name,
    '__init__': Test_init,
}, parent=Object)

test = Instance(Test, kwargs={'name': 'hullo'})

print('get_name:', test.call_method('get_name'))
print('typeof:', test.call_method('typeof'))
print('set_name', test.call_method('set_name', args=('world',)))
print('get_name:', test.call_method('get_name'))