How can namedtuples be extended or subclassed with many additional @properties ?
For a few, one can just write the text below; but there are many, so I'm looking for a generator or property factory. One way would be to generate text from _fields and exec it; another would be an add_fields with the same effect at runtime.
(My @props are to get rows and fields in a database scattered across several tables, so that rec.pname is persontable[rec.personid].pname; but namedtuples-with-smart-fields would have other uses too.) 

""" extend namedtuple with many @properties ? """
from collections import namedtuple

Person = namedtuple( "Person", "pname paddr" )  # ...
persontable = [
    Person( "Smith", "NY" ),
    Person( "Jones", "IL" )
    ]

class Top( namedtuple( "Top_", "topid amount personid" )):
    """ @property 
        .person -> persontable[personid]
        .pname -> person.pname ...
    """
    __slots__ = ()
    @property
    def person(self):
        return persontable[self.personid]

    # def add_fields( self, Top.person, Person._fields ) with the same effect as these ?
    @property
    def pname(self):
        return self.person.pname
    @property
    def paddr(self):
        return self.person.paddr
    # ... many more

rec = Top( 0, 42, 1 )
print rec.person, rec.pname, rec.paddr
python properties namedtuple
Edit
Report