[Jython-dev] Comments about the new __iter__ protocol.

[<bc...@wo...>]

Hi,

In the last bunch of iterator related checkins, I have not added any
backward compatibility for existing PyObject subclasses that uses the
__finditem__ protocol to support looping.

As much as I would like to forget about this kind of backward
compatibility, I don't honestly believe I can get away with it.

Right now, a PyObject subclass *must* implement the __iter__ protocol if
it wish to participate in a sequence operation. If the subclass already
defines __finditem__, it can support the new __iter__ protocol by adding
a method like this:

    public PyObject __iter__() {
        return new PySequenceIter(this);
    }

I would like some suggestions on how we can stay backward compatible on
the API protocol level, without putting too big a burden on new PyObject
subclasses.

regards,
finn