Iterators phase 1. This comprises:

new slot tp_iter in type object, plus new flag Py_TPFLAGS_HAVE_ITER
new C API PyObject_GetIter(), calls tp_iter
new builtin iter(), with two forms: iter(obj), and iter(function, sentinel)
new internal object types iterobject and calliterobject
new exception StopIteration
new opcodes for "for" loops, GET_ITER and FOR_ITER (also supported by dis.py)
new magic number for .pyc files
new special method for instances: __iter__() returns an iterator
iteration over dictionaries: "for x in dict" iterates over the keys
iteration over files: "for x in file" iterates over lines

TODO:

documentation
test suite
decide whether to use a different way to spell iter(function, sentinal)
decide whether "for key in dict" is a good idea
use iterators in map/filter/reduce, min/max, and elsewhere (in/not in?)
speed tuning (make next() a slot tp_next???)

1 files changed, 29 insertions, 2 deletions

diff --git a/Objects/classobject.c b/Objects/classobject.c
index fa71c4e..742e472 100644
--- a/Objects/classobject.c
+++ b/Objects/classobject.c
@@ -848,7 +848,7 @@ instance_traverse(PyInstanceObject *o, visitproc visit, void *arg)
 	return 0;
 }
 
-static PyObject *getitemstr, *setitemstr, *delitemstr, *lenstr;
+static PyObject *getitemstr, *setitemstr, *delitemstr, *lenstr, *iterstr;
 
 static int
 instance_length(PyInstanceObject *inst)
@@ -1712,6 +1712,32 @@ instance_richcompare(PyObject *v, PyObject *w, int op)
 }
 
 
+/* Get the iterator */
+static PyObject *
+instance_getiter(PyInstanceObject *self)
+{
+	PyObject *func;
+
+	if (iterstr == NULL)
+		iterstr = PyString_InternFromString("__iter__");
+	if (getitemstr == NULL)
+		getitemstr = PyString_InternFromString("__getitem__");
+
+	if ((func = instance_getattr(self, iterstr)) != NULL) {
+		PyObject *res = PyEval_CallObject(func, (PyObject *)NULL);
+		Py_DECREF(func);
+		return res;
+	}
+	PyErr_Clear();
+	if ((func = instance_getattr(self, getitemstr)) == NULL) {
+		PyErr_SetString(PyExc_TypeError, "iter() of non-sequence");
+		return NULL;
+	}
+	Py_DECREF(func);
+	return PyIter_New((PyObject *)self);
+}
+
+
 static PyNumberMethods instance_as_number = {
 	(binaryfunc)instance_add,		/* nb_add */
 	(binaryfunc)instance_sub,		/* nb_subtract */
@@ -1775,7 +1801,8 @@ PyTypeObject PyInstance_Type = {
 	(traverseproc)instance_traverse,	/* tp_traverse */
 	0,					/* tp_clear */
 	instance_richcompare,			/* tp_richcompare */
- 	offsetof(PyInstanceObject, in_weakreflist) /* tp_weaklistoffset */
+ 	offsetof(PyInstanceObject, in_weakreflist), /* tp_weaklistoffset */
+	(getiterfunc)instance_getiter,		/* tp_iter */
 };