Temporarily disable instance caching in :meth:`~.Expression.create`

    Within the managed context, :meth:`~.Expression.create` will not use any
    caching, for any class.

def no_instance_caching():
    """Temporarily disable instance caching in :meth:`~.Expression.create`

    Within the managed context, :meth:`~.Expression.create` will not use any
    caching, for any class.
    """
    # this assumes that no sub-class of Expression shadows
    # Expression.instance_caching
    orig_flag = Expression.instance_caching
    Expression.instance_caching = False
    try:
        yield
    finally:
        Expression.instance_caching = orig_flag