Mine

def extend_fields(fields, path=None):

    def save_desc(self, desc, *args, **kwargs):
        self.desc = desc.decode('utf-8')
        self.__init_orig__(*args, **kwargs)

    for field in fields:
        if path:
            exec('from %s import %s' % (path, field))
            cls = locals()[field]
            globals()[field] = cls
        else:
            cls = globals()[field]
        cls.__init_orig__ = cls.__init__
        cls.__init__ = save_desc


extend_fields(
    ('CharField', 'DateField', 'EmailField', 'ChoiceField'),
    path='django.newforms.fields'
)