How to avoid monkey-patching sqlalchemy.ext.declarative.api._as_declarative

sqla_ca.py

import sqlalchemy as sa
import sqlalchemy.ext.declarative

"""
How to avoid monkey-patching sqlalchemy.ext.declarative.api._as_declarative???
"""

USE_EVENT=True

if USE_EVENT:
    @sa.event.listens_for(sa.orm.mapper, "mapper_configured")
    def _setup_tefproperties(mapper, class_):
        for key, value in class_.__dict__.items():
            if isinstance(value, TefProperty):
                value._config(class_, key)

else:
    _as_declarative_orig = sqlalchemy.ext.declarative.api._as_declarative
    def _as_declarative_tef(cls, classname, dict_):
        dict_ = dict(dict_)
        for key, value in cls.__dict__.items():
            if isinstance(value, TefProperty):
                dict_[key] = value._config(cls, key)
        return _as_declarative_orig(cls, classname, dict_)

    sqlalchemy.ext.declarative.api._as_declarative = _as_declarative_tef



Base = sqlalchemy.ext.declarative.declarative_base(mapper=sa.orm.mapper)
engine = sa.create_engine('sqlite:///:memory:', echo = True)

class TefProperty(object):
    def _config(self, cls, key):
        col = sa.Column(key, self.sqla_type)
        setattr(cls, key, col)
        return col

class propInt(TefProperty):
    sqla_type = sa.types.Integer

class propStr(TefProperty):
    sqla_type = sa.types.String

class Foo(Base):
    __tablename__ = 'foo'
    id = sa.Column( sa.types.Integer, primary_key=True)
    intprop = propInt()
    strprop = propStr()

Base.metadata.create_all(engine, checkfirst=True)

Session = sa.orm.sessionmaker(
    bind = engine,
    autocommit = False,
)

session = Session()

session.query(Foo).filter(Foo.intprop + Foo.intprop, Foo.strprop + Foo.strprop).all()

https://groups.google.com/d/topic/sqlalchemy/G2jC0tn-EX8/discussion