`has_inherited_table` should probably skip checking the current class

[Sok Ann Yap]

The has_inherited_table checking is done using for-loop:

for class_ in cls.__mro__:

I think this should be changed to:

for class_ in cls.__mro__[1:](1:):

Otherwise, the function seems to be only useful during the class mapping stage.

Here's a slightly modified code sample based on the example at http://docs.sqlalchemy.org/en/rel_0_7/orm/extensions/declarative.html#controlling-table-inheritance-with-mixins:

from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.ext.declarative import declared_attr
from sqlalchemy.ext.declarative import has_inherited_table
from sqlalchemy.schema import Column
from sqlalchemy.types import Integer, String

Base = declarative_base()

class Tablename(object):
    @declared_attr
    def __tablename__(cls):
        print cls.__name__, has_inherited_table(cls)
        if has_inherited_table(cls):
            return None
        return cls.__name__.lower()

class Person(Tablename, Base):
    id = Column(Integer, primary_key=True)
    discriminator = Column('type', String(50))
    __mapper_args__ = {'polymorphic_on': discriminator}

class Engineer(Person):
    primary_language = Column(String(50))
    __mapper_args__ = {'polymorphic_identity': 'engineer'}

for cls in (Person, Engineer):
    print cls.__name__, has_inherited_table(cls)

With cls.__mro__, the output is:

Person False
Engineer True
Person True
Engineer True

With cls.__mro__[1:](1:), the output is:

Person False
Engineer True
Person False
Engineer True

[Mike Bayer]

hmmm OK , well the function was only intended to be used during the class mapping stage, but if you want to use it elsewhere, I can make this change for 0.8 hows that ?

[Sok Ann Yap]

Cool. I was going to use it in a Table's after_create event, which I added for all the model classes (DB2 for z/OS has this annoying behavior such that if a table is created in an explicitly specified tablespace, a unique index has to be created separately for each primary key / unique constraint)

[Mike Bayer]

unfortunately, this is actually a regression, wish I knew this before we released:

from sqlalchemy import *
from sqlalchemy.orm import configure_mappers
from sqlalchemy.ext.declarative import (declarative_base,
    declared_attr, has_inherited_table)

Base = declarative_base()

class Test(Base):
    __tablename__ = 'test'
    id = Column(Integer, primary_key=True)
    type = Column(String(20))

    @declared_attr
    def __mapper_args__(cls):
        if not has_inherited_table(cls):
            ret = {
                'polymorphic_identity': 'default',
                'polymorphic_on': cls.type,
                }
        else:
            ret = {'polymorphic_identity': cls.__name__}
        return ret

class PolyTest(Test):
    __tablename__ = 'poly_test'
    id = Column(Integer, ForeignKey(Test.id), primary_key=True)

configure_mappers()

assert Test.__mapper__.polymorphic_on is Test.__table__.c.type
assert PolyTest.__mapper__.polymorphic_on is Test.__table__.c.type

[Mike Bayer]

d84ae4f75468fea6b3345c1275d6a472d0cf7c5f

[Mike Bayer]

Removing milestone: 0.8.xx (automated comment)