From a1351fbd884189329bbcb6c688ca992fc1afc3f6 Mon Sep 17 00:00:00 2001 From: Guido van Rossum Date: Tue, 20 Mar 2001 12:41:34 +0000 Subject: SF patch #408326 by Robin Thomas: slice objects comparable, not hashable This patch changes the behavior of slice objects in the following manner: - Slice objects are now comparable with other slice objects as though they were logically tuples of (start,stop,step). The tuple is not created in the comparison function, but the comparison behavior is logically equivalent. - Slice objects are not hashable. With the above change to being comparable, slice objects now cannot be used as keys in dictionaries. [I've edited the patch for style. Note that this fixes the problem that dict[i:j] seemed to work but was meaningless. --GvR] --- Objects/sliceobject.c | 26 +++++++++++++++++++++++--- 1 file changed, 23 insertions(+), 3 deletions(-) diff --git a/Objects/sliceobject.c b/Objects/sliceobject.c index bb94e42..6f7a6d8 100644 --- a/Objects/sliceobject.c +++ b/Objects/sliceobject.c @@ -155,6 +155,26 @@ static PyObject *slice_getattr(PySliceObject *self, char *name) return ret; } +static int +slice_compare(PySliceObject *v, PySliceObject *w) +{ + int result = 0; + + if (v == w) + return 0; + + if (PyObject_Cmp(v->start, w->start, &result) < 0) + return -2; + if (result != 0) + return result; + if (PyObject_Cmp(v->stop, w->stop, &result) < 0) + return -2; + if (result != 0) + return result; + if (PyObject_Cmp(v->step, w->step, &result) < 0) + return -2; + return result; +} PyTypeObject PySlice_Type = { PyObject_HEAD_INIT(&PyType_Type) @@ -166,9 +186,9 @@ PyTypeObject PySlice_Type = { 0, /*tp_print*/ (getattrfunc)slice_getattr, /*tp_getattr*/ 0, /*tp_setattr*/ - 0, /*tp_compare*/ - (reprfunc)slice_repr, /*tp_repr*/ + (cmpfunc)slice_compare, /*tp_compare*/ + (reprfunc)slice_repr, /*tp_repr*/ 0, /*tp_as_number*/ - 0, /*tp_as_sequence*/ + 0, /*tp_as_sequence*/ 0, /*tp_as_mapping*/ }; -- cgit v0.12