From: Mike Bayer <mike_mp@zzzcomputing.com>
Date: Mon, 9 Aug 2010 00:58:05 +0000 (-0400)
Subject: - modernizing examples
X-Git-Tag: rel_0_6_4~45
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c14a3651a4ea624e0539c4ee7d45e23bf6139403;p=thirdparty%2Fsqlalchemy%2Fsqlalchemy.git

- modernizing examples
---

diff --git a/examples/derived_attributes/attributes.py b/examples/derived_attributes/attributes.py
index 15af7b2adb..ade2a4ed31 100644
--- a/examples/derived_attributes/attributes.py
+++ b/examples/derived_attributes/attributes.py
@@ -1,7 +1,7 @@
 
 import new
 
-class MethodDescriptor(object):
+class hybrid(object):
     def __init__(self, func):
         self.func = func
     def __get__(self, instance, owner):
@@ -10,8 +10,8 @@ class MethodDescriptor(object):
         else:
             return new.instancemethod(self.func, instance, owner)
 
-class PropertyDescriptor(object):
-    def __init__(self, fget, fset, fdel):
+class hybrid_property(object):
+    def __init__(self, fget, fset=None, fdel=None):
         self.fget = fget
         self.fset = fset
         self.fdel = fdel
@@ -24,17 +24,15 @@ class PropertyDescriptor(object):
         self.fset(instance, value)
     def __delete__(self, instance):
         self.fdel(instance)
-        
-def hybrid(func):
-    return MethodDescriptor(func)
-
-def hybrid_property(fget, fset=None, fdel=None):
-    return PropertyDescriptor(fget, fset, fdel)
+    
+    def setter(self, fset):
+        self.fset = fset
+        return self
 
 ### Example code
 
 from sqlalchemy import MetaData, Table, Column, Integer
-from sqlalchemy.orm import mapper, create_session
+from sqlalchemy.orm import mapper, sessionmaker
 
 metadata = MetaData('sqlite://')
 metadata.bind.echo = True
@@ -91,7 +89,7 @@ mapper(Interval2, interval_table2)
 
 print "Create the data"
 
-session = create_session()
+session = sessionmaker()()
 
 intervals = [Interval1(1,4), Interval1(3,15), Interval1(11,16)]
 
@@ -99,18 +97,16 @@ for interval in intervals:
     session.add(interval)
     session.add(Interval2(interval.start, interval.length))
 
-session.flush()
-
-print "Clear the cache and do some queries"
+session.commit()
 
-session.expunge_all()
 
 for Interval in (Interval1, Interval2):
     print "Querying using interval class %s" % Interval.__name__
     
     print
     print '-- length less than 10'
-    print [(i, i.length) for i in session.query(Interval).filter(Interval.length < 10).all()]
+    print [(i, i.length) for i in 
+                session.query(Interval).filter(Interval.length < 10).all()]
     
     print
     print '-- contains 12'
@@ -119,6 +115,8 @@ for Interval in (Interval1, Interval2):
     print
     print '-- intersects 2..10'
     other = Interval1(2,10)
-    result = session.query(Interval).filter(Interval.intersects(other)).order_by(Interval.length).all()
+    result = session.query(Interval).\
+                    filter(Interval.intersects(other)).\
+                    order_by(Interval.length).all()
     print [(interval, interval.intersects(other)) for interval in result]
 
diff --git a/examples/inheritance/concrete.py b/examples/inheritance/concrete.py
index c50513b555..eb832a55d9 100644
--- a/examples/inheritance/concrete.py
+++ b/examples/inheritance/concrete.py
@@ -1,5 +1,6 @@
-from sqlalchemy import create_engine, MetaData, Table, Column, Integer, String
-from sqlalchemy.orm import mapper, create_session, polymorphic_union
+from sqlalchemy import create_engine, MetaData, Table, Column, Integer, \
+    String
+from sqlalchemy.orm import mapper, sessionmaker, polymorphic_union
 
 metadata = MetaData()
 
@@ -30,14 +31,16 @@ class Manager(Employee):
         self.name = name
         self.manager_data = manager_data
     def __repr__(self):
-        return self.__class__.__name__ + " " + self.name + " " +  self.manager_data
+        return self.__class__.__name__ + " " + \
+                    self.name + " " +  self.manager_data
     
 class Engineer(Employee):
     def __init__(self, name, engineer_info):
         self.name = name
         self.engineer_info = engineer_info
     def __repr__(self):
-        return self.__class__.__name__ + " " + self.name + " " +  self.engineer_info
+        return self.__class__.__name__ + " " + \
+                    self.name + " " +  self.engineer_info
 
 
 pjoin = polymorphic_union({
@@ -46,11 +49,15 @@ pjoin = polymorphic_union({
 }, 'type', 'pjoin')
 
 employee_mapper = mapper(Employee, pjoin, polymorphic_on=pjoin.c.type)
-manager_mapper = mapper(Manager, managers_table, inherits=employee_mapper, concrete=True, polymorphic_identity='manager')
-engineer_mapper = mapper(Engineer, engineers_table, inherits=employee_mapper, concrete=True, polymorphic_identity='engineer')
+manager_mapper = mapper(Manager, managers_table,
+                        inherits=employee_mapper, concrete=True,
+                        polymorphic_identity='manager')
+engineer_mapper = mapper(Engineer, engineers_table,
+                         inherits=employee_mapper, concrete=True,
+                         polymorphic_identity='engineer')
 
 
-session = create_session(bind=engine)
+session = sessionmaker(engine)()
 
 m1 = Manager("pointy haired boss", "manager1")
 e1 = Engineer("wally", "engineer1")
@@ -59,8 +66,7 @@ e2 = Engineer("dilbert", "engineer2")
 session.add(m1)
 session.add(e1)
 session.add(e2)
-session.flush()
+session.commit()
 
-employees = session.query(Employee)
-print [e for e in employees]
+print session.query(Employee).all()
 
diff --git a/examples/inheritance/polymorph.py b/examples/inheritance/polymorph.py
index 7ca207f9fd..8723180604 100644
--- a/examples/inheritance/polymorph.py
+++ b/examples/inheritance/polymorph.py
@@ -1,19 +1,20 @@
-from sqlalchemy import MetaData, Table, Column, Integer, String, ForeignKey
-from sqlalchemy.orm import mapper, relationship, create_session
-import sets
+from sqlalchemy import MetaData, Table, Column, Integer, String, \
+    ForeignKey, create_engine
+from sqlalchemy.orm import mapper, relationship, sessionmaker
+
 
 # this example illustrates a polymorphic load of two classes
 
-metadata = MetaData('sqlite://')
-metadata.bind.echo = True
+metadata = MetaData()
 
 # a table to store companies
 companies = Table('companies', metadata, 
    Column('company_id', Integer, primary_key=True),
    Column('name', String(50)))
 
-# we will define an inheritance relationship between the table "people" and "engineers",
-# and a second inheritance relationship between the table "people" and "managers"
+# we will define an inheritance relationship between the table "people" and
+# "engineers", and a second inheritance relationship between the table
+# "people" and "managers"
 people = Table('people', metadata, 
    Column('person_id', Integer, primary_key=True),
    Column('company_id', Integer, ForeignKey('companies.company_id')),
@@ -21,20 +22,20 @@ people = Table('people', metadata,
    Column('type', String(30)))
    
 engineers = Table('engineers', metadata, 
-   Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
+   Column('person_id', Integer, ForeignKey('people.person_id'), 
+                                    primary_key=True),
    Column('status', String(30)),
    Column('engineer_name', String(50)),
    Column('primary_language', String(50)),
   )
    
 managers = Table('managers', metadata, 
-   Column('person_id', Integer, ForeignKey('people.person_id'), primary_key=True),
+   Column('person_id', Integer, ForeignKey('people.person_id'), 
+                                    primary_key=True),
    Column('status', String(30)),
    Column('manager_name', String(50))
    )
    
-metadata.create_all()
-
 # create our classes.  The Engineer and Manager classes extend from Person.
 class Person(object):
     def __init__(self, **kwargs):
@@ -44,10 +45,14 @@ class Person(object):
         return "Ordinary person %s" % self.name
 class Engineer(Person):
     def __repr__(self):
-        return "Engineer %s, status %s, engineer_name %s, primary_language %s" % (self.name, self.status, self.engineer_name, self.primary_language)
+        return "Engineer %s, status %s, engineer_name %s, "\
+                "primary_language %s" % \
+                    (self.name, self.status, 
+                        self.engineer_name, self.primary_language)
 class Manager(Person):
     def __repr__(self):
-        return "Manager %s, status %s, manager_name %s" % (self.name, self.status, self.manager_name)
+        return "Manager %s, status %s, manager_name %s" % \
+                    (self.name, self.status, self.manager_name)
 class Company(object):
     def __init__(self, **kwargs):
         for key, value in kwargs.iteritems():
@@ -56,30 +61,43 @@ class Company(object):
         return "Company %s" % self.name
 
 
-person_mapper = mapper(Person, people, polymorphic_on=people.c.type, polymorphic_identity='person')
-mapper(Engineer, engineers, inherits=person_mapper, polymorphic_identity='engineer')
-mapper(Manager, managers, inherits=person_mapper, polymorphic_identity='manager')
+person_mapper = mapper(Person, people, polymorphic_on=people.c.type,
+                       polymorphic_identity='person')
+mapper(Engineer, engineers, inherits=person_mapper,
+       polymorphic_identity='engineer')
+mapper(Manager, managers, inherits=person_mapper,
+       polymorphic_identity='manager')
+
+mapper(Company, companies, properties={'employees'
+       : relationship(Person, lazy='joined', backref='company',
+       cascade='all, delete-orphan')})
+
+engine = create_engine('sqlite://', echo=True)
+
+metadata.create_all(engine)
 
-mapper(Company, companies, properties={
-    'employees': relationship(Person, lazy='joined', backref='company', cascade="all, delete-orphan")
-})
+session = sessionmaker(engine)()
 
-session = create_session()
 c = Company(name='company1')
-c.employees.append(Manager(name='pointy haired boss', status='AAB', manager_name='manager1'))
-c.employees.append(Engineer(name='dilbert', status='BBA', engineer_name='engineer1', primary_language='java'))
+c.employees.append(Manager(name='pointy haired boss', status='AAB',
+                   manager_name='manager1'))
+c.employees.append(Engineer(name='dilbert', status='BBA',
+                   engineer_name='engineer1', primary_language='java'))
 c.employees.append(Person(name='joesmith', status='HHH'))
-c.employees.append(Engineer(name='wally', status='CGG', engineer_name='engineer2', primary_language='python'))
-c.employees.append(Manager(name='jsmith', status='ABA', manager_name='manager2'))
+c.employees.append(Engineer(name='wally', status='CGG',
+                   engineer_name='engineer2', primary_language='python'
+                   ))
+c.employees.append(Manager(name='jsmith', status='ABA',
+                   manager_name='manager2'))
 session.add(c)
 
-session.flush()
-session.expunge_all()
+session.commit()
 
 c = session.query(Company).get(1)
 for e in c.employees:
     print e, e._sa_instance_state.key, e.company
-assert sets.Set([e.name for e in c.employees]) == sets.Set(['pointy haired boss', 'dilbert', 'joesmith', 'wally', 'jsmith'])
+assert set([e.name for e in c.employees]) == set(['pointy haired boss',
+        'dilbert', 'joesmith', 'wally', 'jsmith'])
 print "\n"
 
 dilbert = session.query(Person).filter_by(name='dilbert').one()
@@ -88,14 +106,12 @@ assert dilbert is dilbert2
 
 dilbert.engineer_name = 'hes dibert!'
 
-session.flush()
-session.expunge_all()
+session.commit()
 
 c = session.query(Company).get(1)
 for e in c.employees:
     print e
 
 session.delete(c)
-session.flush()
+session.commit()
 
-metadata.drop_all()
diff --git a/examples/inheritance/single.py b/examples/inheritance/single.py
index 29b214b209..a7883fcbff 100644
--- a/examples/inheritance/single.py
+++ b/examples/inheritance/single.py
@@ -1,8 +1,8 @@
-from sqlalchemy import MetaData, Table, Column, Integer, String, ForeignKey
-from sqlalchemy.orm import mapper, relationship, create_session
+from sqlalchemy import MetaData, Table, Column, Integer, String, \
+    ForeignKey, create_engine
+from sqlalchemy.orm import mapper, relationship, sessionmaker
 
-metadata = MetaData('sqlite://')
-metadata.bind.echo = 'debug'
+metadata = MetaData()
 
 # a table to store companies
 companies = Table('companies', metadata, 
@@ -20,7 +20,6 @@ employees_table = Table('employees', metadata,
     Column('manager_name', String(50))
 )
 
-metadata.create_all()
 
 class Person(object):
     def __init__(self, **kwargs):
@@ -30,10 +29,14 @@ class Person(object):
         return "Ordinary person %s" % self.name
 class Engineer(Person):
     def __repr__(self):
-        return "Engineer %s, status %s, engineer_name %s, primary_language %s" % (self.name, self.status, self.engineer_name, self.primary_language)
+        return "Engineer %s, status %s, engineer_name %s, "\
+                    "primary_language %s" % \
+                        (self.name, self.status, 
+                        self.engineer_name, self.primary_language)
 class Manager(Person):
     def __repr__(self):
-        return "Manager %s, status %s, manager_name %s" % (self.name, self.status, self.manager_name)
+        return "Manager %s, status %s, manager_name %s" % \
+                    (self.name, self.status, self.manager_name)
 class Company(object):
     def __init__(self, **kwargs):
         for key, value in kwargs.iteritems():
@@ -41,25 +44,38 @@ class Company(object):
     def __repr__(self):
         return "Company %s" % self.name
 
-person_mapper = mapper(Person, employees_table, polymorphic_on=employees_table.c.type, polymorphic_identity='person')
-manager_mapper = mapper(Manager, inherits=person_mapper, polymorphic_identity='manager')
-engineer_mapper = mapper(Engineer, inherits=person_mapper, polymorphic_identity='engineer')
+person_mapper = mapper(Person, employees_table,
+                       polymorphic_on=employees_table.c.type,
+                       polymorphic_identity='person')
+manager_mapper = mapper(Manager, inherits=person_mapper,
+                        polymorphic_identity='manager')
+engineer_mapper = mapper(Engineer, inherits=person_mapper,
+                         polymorphic_identity='engineer')
 
 mapper(Company, companies, properties={
     'employees': relationship(Person, lazy=True, backref='company')
 })
 
-session = create_session()
+
+engine = create_engine('sqlite:///', echo=True)
+
+metadata.create_all(engine)
+
+session = sessionmaker(engine)()
+
 c = Company(name='company1')
-c.employees.append(Manager(name='pointy haired boss', status='AAB', manager_name='manager1'))
-c.employees.append(Engineer(name='dilbert', status='BBA', engineer_name='engineer1', primary_language='java'))
+c.employees.append(Manager(name='pointy haired boss', status='AAB',
+                   manager_name='manager1'))
+c.employees.append(Engineer(name='dilbert', status='BBA',
+                   engineer_name='engineer1', primary_language='java'))
 c.employees.append(Person(name='joesmith', status='HHH'))
-c.employees.append(Engineer(name='wally', status='CGG', engineer_name='engineer2', primary_language='python'))
-c.employees.append(Manager(name='jsmith', status='ABA', manager_name='manager2'))
+c.employees.append(Engineer(name='wally', status='CGG',
+                   engineer_name='engineer2', primary_language='python'
+                   ))
+c.employees.append(Manager(name='jsmith', status='ABA',
+                   manager_name='manager2'))
 session.add(c)
-session.flush()
-
-session.expunge_all()
+session.commit()
 
 c = session.query(Company).get(1)
 for e in c.employees:
@@ -81,6 +97,4 @@ for e in c.employees:
     print e
 
 session.delete(c)
-session.flush()
-
-metadata.drop_all()
+session.commit()
diff --git a/examples/poly_assoc/poly_assoc.py b/examples/poly_assoc/poly_assoc.py
index ecdc403e75..1854bfa3d8 100644
--- a/examples/poly_assoc/poly_assoc.py
+++ b/examples/poly_assoc/poly_assoc.py
@@ -1,28 +1,29 @@
 """
 "polymorphic" associations, ala ActiveRecord.
 
-In this example, we are specifically targeting this ActiveRecord functionality:
+In this example, we are specifically targeting this ActiveRecord
+functionality:
 
 http://wiki.rubyonrails.org/rails/pages/UnderstandingPolymorphicAssociations
 
-The term "polymorphic" here means "object X can be referenced by objects A, B, and C,
-along a common line of association".
+The term "polymorphic" here means "object X can be referenced by objects A, B,
+and C, along a common line of association".
 
-In this example we illustrate the relationship in both directions.
-A little bit of property magic is used to smooth the edges.
+In this example we illustrate the relationship in both directions. A little
+bit of property magic is used to smooth the edges.
 
-AR creates this relationship in such a way that disallows
-any foreign key constraint from existing on the association.
-For a different way of doing this,  see
-poly_assoc_fks.py.  The interface is the same, the efficiency is more or less the same,
-but foreign key constraints may be used.  That example also better separates
-the associated target object from those which associate with it.
+AR creates this relationship in such a way that disallows any foreign key
+constraint from existing on the association. For a different way of doing
+this, see poly_assoc_fks.py. The interface is the same, the efficiency is more
+or less the same, but foreign key constraints may be used. That example also
+better separates the associated target object from those which associate with
+it.
 
 """
 
 from sqlalchemy import MetaData, Table, Column, Integer, String, and_
-from sqlalchemy.orm import (mapper, relationship, create_session, class_mapper,
-    backref)
+from sqlalchemy.orm import mapper, relationship, sessionmaker, \
+    class_mapper, backref
 
 metadata = MetaData('sqlite://')
 
@@ -41,12 +42,15 @@ addresses = Table("addresses", metadata,
 class Address(object):
     def __init__(self, type):
         self.addressable_type = type
-    member = property(lambda self: getattr(self, '_backref_%s' % self.addressable_type))
+    @property
+    def member(self):
+        return getattr(self, '_backref_%s' % self.addressable_type)
 
 def addressable(cls, name, uselist=True):
     """addressable 'interface'.
 
-    if you really wanted to make a "generic" version of this function, it's straightforward.
+    if you really wanted to make a "generic" version of this function, it's
+    straightforward.
     """
 
     # create_address function, imitaes the rails example.
@@ -71,8 +75,13 @@ def addressable(cls, name, uselist=True):
     foreign_keys = [addresses.c.addressable_id]
     mapper.add_property(name, relationship(
             Address,
-            primaryjoin=primaryjoin, uselist=uselist, foreign_keys=foreign_keys,
-            backref=backref('_backref_%s' % table.name, primaryjoin=list(table.primary_key)[0] == addresses.c.addressable_id, foreign_keys=foreign_keys)
+            primaryjoin=primaryjoin, 
+            uselist=uselist, 
+            foreign_keys=foreign_keys,
+            backref=backref('_backref_%s' % table.name, 
+                            primaryjoin=list(table.primary_key)[0] ==\
+                                        addresses.c.addressable_id, 
+                            foreign_keys=foreign_keys)
         )
     )
 
@@ -124,12 +133,11 @@ a2.street = '345 orchard ave'
 a3 = o1.create_address()
 a3.street = '444 park ave.'
 
-sess = create_session()
+sess = sessionmaker()()
 sess.add(u1)
 sess.add(o1)
-sess.flush()
 
-sess.expunge_all()
+sess.commit()
 
 # query objects, get their addresses
 
diff --git a/examples/poly_assoc/poly_assoc_fk.py b/examples/poly_assoc/poly_assoc_fk.py
index 96c9935c30..a22020e088 100644
--- a/examples/poly_assoc/poly_assoc_fk.py
+++ b/examples/poly_assoc/poly_assoc_fk.py
@@ -1,26 +1,26 @@
 """
 "polymorphic" associations, ala SQLAlchemy.
 
-See "poly_assoc.py" for an imitation of this functionality as implemented
-in ActiveRecord.
-
-Here, we build off the previous example, adding an association table
-that allows the relationship to be expressed as a many-to-one from the
-"model" object to its "association", so that each model table bears the foreign
-key constraint.  This allows the same functionality via traditional
-normalized form with full constraints.  It also isolates the target
-associated object from its method of being associated, allowing greater
-flexibility in its usage.
-
-As in the previous example, a little bit of property magic is used
-to smooth the edges.
-
-For a more genericized version of this example, see
-poly_assoc_generic.py.
+See "poly_assoc.py" for an imitation of this functionality as implemented in
+ActiveRecord.
+
+Here, we build off the previous example, adding an association table that
+allows the relationship to be expressed as a many-to-one from the "model"
+object to its "association", so that each model table bears the foreign key
+constraint. This allows the same functionality via traditional normalized form
+with full constraints. It also isolates the target associated object from its
+method of being associated, allowing greater flexibility in its usage.
+
+As in the previous example, a little bit of property magic is used to smooth
+the edges.
+
+For a more genericized version of this example, see poly_assoc_generic.py.
 """
 
-from sqlalchemy import MetaData, Table, Column, Integer, String, ForeignKey
-from sqlalchemy.orm import mapper, relationship, create_session, class_mapper
+from sqlalchemy import MetaData, Table, Column, Integer, String, \
+    ForeignKey
+from sqlalchemy.orm import mapper, relationship, sessionmaker, \
+    class_mapper
 
 metadata = MetaData('sqlite://')
 
@@ -42,7 +42,11 @@ address_associations = Table("address_associations", metadata,
 )
 
 class Address(object):
-    member = property(lambda self: getattr(self.association, '_backref_%s' % self.association.type))
+
+    @property
+    def member(self):
+        return getattr(self.association, '_backref_%s'
+                       % self.association.type)
 
 class AddressAssoc(object):
     def __init__(self, name):
@@ -56,7 +60,10 @@ def addressable(cls, name, uselist=True):
     """
     mapper = class_mapper(cls)
     table = mapper.local_table
-    mapper.add_property('address_rel', relationship(AddressAssoc, backref='_backref_%s' % table.name))
+    mapper.add_property('address_rel', 
+                        relationship(AddressAssoc, 
+                                backref='_backref_%s' % table.name)
+                        )
 
     if uselist:
         # list based property decorator
@@ -88,7 +95,7 @@ users = Table("users", metadata,
     Column('id', Integer, primary_key=True),
     Column('name', String(50), nullable=False),
     # this column ties the users table into the address association
-    Column('assoc_id', None, ForeignKey('address_associations.assoc_id'))
+    Column('assoc_id', Integer, ForeignKey('address_associations.assoc_id'))
     )
 
 class User(object):
@@ -104,7 +111,7 @@ orders = Table("orders", metadata,
     Column('id', Integer, primary_key=True),
     Column('description', String(50), nullable=False),
     # this column ties the orders table into the address association
-    Column('assoc_id', None, ForeignKey('address_associations.assoc_id'))
+    Column('assoc_id', Integer, ForeignKey('address_associations.assoc_id'))
     )
 
 class Order(object):
@@ -136,17 +143,17 @@ a2.street = '345 orchard ave'
 o1.address = Address()
 o1.address.street = '444 park ave.'
 
-sess = create_session()
+sess = sessionmaker()()
 sess.add(u1)
 sess.add(o1)
-sess.flush()
 
-sess.expunge_all()
+sess.commit()
 
 # query objects, get their addresses
 
 bob = sess.query(User).filter_by(name='bob').one()
-assert [s.street for s in bob.addresses] == ['123 anywhere street', '345 orchard ave']
+assert [s.street for s in bob.addresses] == \
+            ['123 anywhere street', '345 orchard ave']
 
 order = sess.query(Order).filter_by(description='order 1').one()
 assert order.address.street == '444 park ave.'
diff --git a/examples/poly_assoc/poly_assoc_generic.py b/examples/poly_assoc/poly_assoc_generic.py
index 235c21becc..aaa182df0a 100644
--- a/examples/poly_assoc/poly_assoc_generic.py
+++ b/examples/poly_assoc/poly_assoc_generic.py
@@ -1,13 +1,14 @@
 """
 "polymorphic" associations, ala SQLAlchemy.
 
-This example generalizes the function in poly_assoc_pk.py into a
-function "association" which creates a new polymorphic association
-"interface".
+This example generalizes the function in poly_assoc_pk.py into a function
+"association" which creates a new polymorphic association "interface".
 """
 
-from sqlalchemy import MetaData, Table, Column, Integer, String, ForeignKey
-from sqlalchemy.orm import mapper, relationship, create_session, class_mapper
+from sqlalchemy import MetaData, Table, Column, Integer, String, \
+    ForeignKey
+from sqlalchemy.orm import mapper, relationship, sessionmaker, \
+    class_mapper
 
 metadata = MetaData('sqlite://')
 
@@ -31,7 +32,10 @@ def association(cls, table):
 
         mapper = class_mapper(cls)
         table = mapper.local_table
-        mapper.add_property(attr_name, relationship(GenericAssoc, backref='_backref_%s' % table.name))
+        mapper.add_property(attr_name, 
+                            relationship(GenericAssoc, 
+                                    backref='_backref_%s' % table.name)
+                            )
 
         if uselist:
             # list based property decorator
@@ -49,8 +53,13 @@ def association(cls, table):
                     setattr(self, attr_name, GenericAssoc(table.name))
                 getattr(self, attr_name).targets = [value]
             setattr(cls, name, property(get, set))
-
-    setattr(cls, 'member', property(lambda self: getattr(self.association, '_backref_%s' % self.association.type)))
+    
+    @property
+    def member(self):
+        return getattr(self.association, 
+                    '_backref_%s' % self.association.type)
+        
+    setattr(cls, 'member', member)
 
     mapper(GenericAssoc, association_table, properties={
         'targets':relationship(cls, backref='association'),
@@ -64,7 +73,7 @@ def association(cls, table):
 
 addresses = Table("addresses", metadata,
     Column('id', Integer, primary_key=True),
-    Column('assoc_id', None, ForeignKey('addresses_associations.assoc_id')),
+    Column('assoc_id', Integer, ForeignKey('addresses_associations.assoc_id')),
     Column('street', String(100)),
     Column('city', String(50)),
     Column('country', String(50))
@@ -85,7 +94,7 @@ mapper(Address, addresses)
 users = Table("users", metadata,
     Column('id', Integer, primary_key=True),
     Column('name', String(50), nullable=False),
-    Column('assoc_id', None, ForeignKey('addresses_associations.assoc_id'))
+    Column('assoc_id', Integer, ForeignKey('addresses_associations.assoc_id'))
     )
 
 class User(object):
@@ -102,7 +111,7 @@ addressable(User, 'addresses', uselist=True)
 orders = Table("orders", metadata,
     Column('id', Integer, primary_key=True),
     Column('description', String(50), nullable=False),
-    Column('assoc_id', None, ForeignKey('addresses_associations.assoc_id'))
+    Column('assoc_id', Integer, ForeignKey('addresses_associations.assoc_id'))
     )
 
 class Order(object):
@@ -132,17 +141,16 @@ a2.street = '345 orchard ave'
 o1.address = Address()
 o1.address.street = '444 park ave.'
 
-sess = create_session()
+sess = sessionmaker()()
 sess.add(u1)
 sess.add(o1)
-sess.flush()
-
-sess.expunge_all()
+sess.commit()
 
 # query objects, get their addresses
 
 bob = sess.query(User).filter_by(name='bob').one()
-assert [s.street for s in bob.addresses] == ['123 anywhere street', '345 orchard ave']
+assert [s.street for s in bob.addresses] == \
+            ['123 anywhere street', '345 orchard ave']
 
 order = sess.query(Order).filter_by(description='order 1').one()
 assert order.address.street == '444 park ave.'
diff --git a/examples/versioning/__init__.py b/examples/versioning/__init__.py
index f0e1cf543b..f2f8832cf7 100644
--- a/examples/versioning/__init__.py
+++ b/examples/versioning/__init__.py
@@ -1,7 +1,12 @@
 """
-Illustrates an extension which creates version tables for entities and stores records for each change.  The same idea as Elixir's versioned extension, but more efficient (uses attribute API to get history) and handles class inheritance.  The given extensions generate an anonymous "history" class which represents historical versions of the target object.   
+Illustrates an extension which creates version tables for entities and stores
+records for each change. The same idea as Elixir's versioned extension, but
+more efficient (uses attribute API to get history) and handles class
+inheritance. The given extensions generate an anonymous "history" class which
+represents historical versions of the target object.
 
-Usage is illustrated via a unit test module ``test_versioning.py``, which can be run via nose::
+Usage is illustrated via a unit test module ``test_versioning.py``, which can
+be run via nose::
 
     nosetests -w examples/versioning/
 
@@ -38,7 +43,8 @@ A fragment of example usage, using declarative::
                 all() \\
                 == [SomeClassHistory(version=1, name='sc1')]
 
-To apply ``VersionedMeta`` to a subset of classes (probably more typical), the metaclass can be applied on a per-class basis::
+To apply ``VersionedMeta`` to a subset of classes (probably more typical), the
+metaclass can be applied on a per-class basis::
 
     from history_meta import VersionedMeta, VersionedListener
 
@@ -55,7 +61,8 @@ To apply ``VersionedMeta`` to a subset of classes (probably more typical), the m
 
         # ...
 
-The ``VersionedMeta`` is a declarative metaclass - to use the extension with plain mappers, the ``_history_mapper`` function can be applied::
+The ``VersionedMeta`` is a declarative metaclass - to use the extension with
+plain mappers, the ``_history_mapper`` function can be applied::
 
     from history_meta import _history_mapper
 
diff --git a/examples/versioning/history_meta.py b/examples/versioning/history_meta.py
index 8a916791c3..a7b03c5bfc 100644
--- a/examples/versioning/history_meta.py
+++ b/examples/versioning/history_meta.py
@@ -13,7 +13,7 @@ def col_references_table(col, table):
 def _history_mapper(local_mapper):
     cls = local_mapper.class_
 
-    # SLIGHT SQLA HACK #1 - set the "active_history" flag
+    # set the "active_history" flag
     # on on column-mapped attributes so that the old version
     # of the info is always loaded (currently sets it on all attributes)
     for prop in local_mapper.iterate_properties:
@@ -117,7 +117,7 @@ def create_version(obj, session, deleted = False):
                 
             obj_col = om.local_table.c[hist_col.key]
 
-            # SLIGHT SQLA HACK #3 - get the value of the
+            # get the value of the
             # attribute based on the MapperProperty related to the
             # mapped column.  this will allow usage of MapperProperties
             # that have a different keyname than that of the mapped column.