models.py

from collections import namedtuple
import json

class Model(object):
    fields = [
        'id',
        'cini',
        'origen',
        'desti'
    ]

    @property
    def ref(self):
        return 1
        
    def __init__(self, *values, **kwvalues):
        stored = namedtuple('{0}_store'.fromat(self.__classname__), self.fields)
        self.store = stored(*values, **kwvalues)
    
    def dump(self, format='json')
        if format == 'json':
            return json.dumps(self.store._asdict())
        else:
            return list(self.store)
    
    def diff(self, obj, fields=None):
        assert isinstance(obj, self.__class__)
        diffs = {}
        if fields is None:
            fields = self.store._fields
        for field in fields:
            self_value = getattr(self, field)
            other_value = getattr(obj, field)
            if self_value != other_value:
                diffs[field] = (self_value, other_value)
            
    def __cmp__(self, other):
        if self.diff(other, ['id', 'cini']):
            return True
        else:
            return False