Method _new_instance

haystack/backends/__init__.py:268–279

This is called to create a new instance of this class when we need new Nodes (or subclasses) in the internal code in this class. Normally, it just shadows __init__(). However, subclasses with an __init__ signature that is not an extension of Node.__init__ might need

(cls, children=None, connector=None, negated=False)

    # We need this because of django.db.models.query_utils.Q. Q. __init__() is
    # problematic, but it is a natural Node subclass in all other respects.
    def _new_instance(cls, children=None, connector=None, negated=False):
        """
        This is called to create a new instance of this class when we need new
        Nodes (or subclasses) in the internal code in this class. Normally, it
        just shadows __init__(). However, subclasses with an __init__ signature
        that is not an extension of Node.__init__ might need to implement this
        method to allow a Node to create a new instance of them (if they have
        any extra setting up to do).
        """
        obj = SearchNode(children, connector, negated)
        obj.__class__ = cls
        return obj

    _new_instance = classmethod(_new_instance)