gistfile1.py

from sqlalchemy.ext.declarative import declarative_base
from history_meta import VersionedMeta, VersionedListener
from sqlalchemy import create_engine, Column, Integer, String, ForeignKey
from sqlalchemy.orm import clear_mappers, compile_mappers, sessionmaker, deferred
if True:
        engine = create_engine("postgresql+pg8000://postgres@localhost:25432/pruebas")
        Base = declarative_base(metaclass=VersionedMeta, bind=engine)
        Session = sessionmaker(extension=VersionedListener())

class SomeTable(Base):
        __tablename__ = "pruebaver"
        id = Column( Integer, primary_key=True)
        nombre = Column(String(50))

        def __init__(self, nombre = ""):
                self.nombre = nombre


if __name__ == "__main__":
        Base.metadata.create_all()
        sess = Session()
        uno = SomeTable( nombre = 'Domingo')
        sess.add(uno )
        sess.commit()
        print uno.version
        uno.nombre = 'Aguilera'
        sess.commit()
        print uno.version
        uno.nombre = "Castillo"
        print uno.version
        sess.commit()
        print uno.version