Merge branch 'getattr'

Things are getting pretty messy, but it's an incremental step towards doing things more
like CPython which should ultimately make things simpler.

The use of the tp_getattro slots (even though they're the CAPI slots) seems to lead to
about a ~7% improvement in interpreter-only speed.

src/asm_writing/assembler.cpp

@@ -737,12 +737,15 @@ void Assembler::cmp(Indirect mem, Immediate imm) {
     emitRex(rex);
     emitByte(0x81);
 
-    assert(-0x80 <= mem.offset && mem.offset < 0x80);
     if (mem.offset == 0) {
         emitModRM(0b00, 7, src_idx);
-    } else {
+    } else if (-0x80 <= mem.offset && mem.offset < 0x80) {
         emitModRM(0b01, 7, src_idx);
         emitByte(mem.offset);
+    } else {
+        assert((-1L << 31) <= mem.offset && mem.offset < (1L << 31) - 1);
+        emitModRM(0b10, 7, src_idx);
+        emitInt(mem.offset, 4);
     }
 
     emitInt(val, 4);

src/capi/typeobject.cpp

@@ -25,6 +25,7 @@ namespace pyston {
 static const std::string _new_str("__new__");
 static const std::string _getattr_str("__getattr__");
 static const std::string _getattribute_str("__getattribute__");
+typedef int (*update_callback)(PyTypeObject*, void*);
 
 extern "C" void conservativeGCHandler(GCVisitor* v, Box* b) noexcept {
     v->visitPotentialRange((void* const*)b, (void* const*)((char*)b + b->cls->tp_basicsize));
@@ -142,6 +143,24 @@ static PyObject* wrap_next(PyObject* self, PyObject* args, void* wrapped) {
     return res;
 }
 
+static PyObject* wrap_descr_get(PyObject* self, PyObject* args, void* wrapped) noexcept {
+    descrgetfunc func = (descrgetfunc)wrapped;
+    PyObject* obj;
+    PyObject* type = NULL;
+
+    if (!PyArg_UnpackTuple(args, "", 1, 2, &obj, &type))
+        return NULL;
+    if (obj == Py_None)
+        obj = NULL;
+    if (type == Py_None)
+        type = NULL;
+    if (type == NULL && obj == NULL) {
+        PyErr_SetString(PyExc_TypeError, "__get__(None, None) is invalid");
+        return NULL;
+    }
+    return (*func)(self, obj, type);
+}
+
 static PyObject* wrap_coercefunc(PyObject* self, PyObject* args, void* wrapped) noexcept {
     coercion func = (coercion)wrapped;
     PyObject* other, *res;
@@ -676,6 +695,25 @@ static PyObject* slot_tp_iternext(PyObject* self) noexcept {
     return call_method(self, "next", &next_str, "()");
 }
 
+static PyObject* slot_tp_descr_get(PyObject* self, PyObject* obj, PyObject* type) noexcept {
+    PyTypeObject* tp = Py_TYPE(self);
+    PyObject* get;
+
+    get = typeLookup(tp, "__get__", NULL);
+    if (get == NULL) {
+        /* Avoid further slowdowns */
+        if (tp->tp_descr_get == slot_tp_descr_get)
+            tp->tp_descr_get = NULL;
+        Py_INCREF(self);
+        return self;
+    }
+    if (obj == NULL)
+        obj = Py_None;
+    if (type == NULL)
+        type = Py_None;
+    return PyObject_CallFunctionObjArgs(get, self, obj, type, NULL);
+}
+
 static PyObject* slot_tp_getattro(PyObject* self, PyObject* name) noexcept {
     static PyObject* getattribute_str = NULL;
     return call_method(self, "__getattribute__", &getattribute_str, "(O)", name);
@@ -707,7 +745,7 @@ static PyObject* call_attribute(PyObject* self, PyObject* attr, PyObject* name)
             attr = descr;
     }
     try {
-        res = runtimeCall(attr, ArgPassSpec(1, 0, true, true), name, NULL, NULL, NULL, NULL);
+        res = runtimeCall(attr, ArgPassSpec(1, 0, false, false), name, NULL, NULL, NULL, NULL);
     } catch (ExcInfo e) {
         setCAPIException(e);
         Py_XDECREF(descr);
@@ -719,8 +757,6 @@ static PyObject* call_attribute(PyObject* self, PyObject* attr, PyObject* name)
 
 static PyObject* slot_tp_getattr_hook(PyObject* self, PyObject* name) noexcept {
     PyObject* getattr, *getattribute, * res = NULL;
-    static PyObject* getattribute_str = NULL;
-    static PyObject* getattr_str = NULL;
 
     /* speed hack: we could use lookup_maybe, but that would resolve the
          method fully for each attribute lookup for classes with
@@ -746,13 +782,9 @@ static PyObject* slot_tp_getattr_hook(PyObject* self, PyObject* name) noexcept {
     } else {
         res = call_attribute(self, getattribute, name);
     }
-    if (res == NULL) {
-        try {
-            res = runtimeCall(getattr, ArgPassSpec(2, 0, true, true), self, name, NULL, NULL, NULL);
-        } catch (ExcInfo e) {
-            setCAPIException(e);
-            return NULL;
-        }
+    if (res == NULL && PyErr_ExceptionMatches(PyExc_AttributeError)) {
+        PyErr_Clear();
+        res = call_attribute(self, getattr, name);
     }
     return res;
 }
@@ -1197,7 +1229,8 @@ static void** slotptr(BoxedClass* type, int offset) noexcept {
     ETSLOT(NAME, as_number.SLOT, FUNCTION, wrap_binaryfunc_r, "x." NAME "(y) <==> " DOC)
 
 static slotdef slotdefs[]
-    = { TPSLOT("__getattr__", tp_getattr, NULL, NULL, ""),
+    = { TPSLOT("__getattribute__", tp_getattr, NULL, NULL, ""),
+        TPSLOT("__getattr__", tp_getattr, NULL, NULL, ""),
         TPSLOT("__setattr__", tp_setattr, NULL, NULL, ""),
         TPSLOT("__delattr__", tp_setattr, NULL, NULL, ""),
 
@@ -1207,6 +1240,8 @@ static slotdef slotdefs[]
                PyWrapperFlag_KEYWORDS),
         TPSLOT("__str__", tp_str, slot_tp_str, wrap_unaryfunc, "x.__str__() <==> str(x)"),
 
+        TPSLOT("__getattribute__", tp_getattro, slot_tp_getattr_hook, wrap_binaryfunc,
+               "x.__getattribute__('name') <==> x.name"),
         TPSLOT("__getattr__", tp_getattro, slot_tp_getattr_hook, NULL, ""),
         TPSLOT("__setattr__", tp_setattro, slot_tp_setattro, wrap_setattr,
                "x.__setattr__('name', value) <==> x.name = value"),
@@ -1221,6 +1256,7 @@ static slotdef slotdefs[]
 
         TPSLOT("__iter__", tp_iter, slot_tp_iter, wrap_unaryfunc, "x.__iter__() <==> iter(x)"),
         TPSLOT("next", tp_iternext, slot_tp_iternext, wrap_next, "x.next() -> the next value, or raise StopIteration"),
+        TPSLOT("__get__", tp_descr_get, slot_tp_descr_get, wrap_descr_get, "descr.__get__(obj[, type]) -> value"),
 
         FLSLOT("__init__", tp_init, slot_tp_init, (wrapperfunc)wrap_init, "x.__init__(...) initializes x; "
                                                                           "see help(type(x)) for signature",
@@ -1461,18 +1497,55 @@ static const slotdef* update_one_slot(BoxedClass* type, const slotdef* p) noexce
     return p;
 }
 
-bool update_slot(BoxedClass* self, const std::string& attr) noexcept {
-    bool updated = false;
-    for (const slotdef& p : slotdefs) {
-        if (!p.name)
-            continue;
-        if (p.name == attr) {
-            // TODO update subclasses;
-            update_one_slot(self, &p);
-            updated = true;
-        }
+/* In the type, update the slots whose slotdefs are gathered in the pp array.
+   This is a callback for update_subclasses(). */
+static int update_slots_callback(PyTypeObject* type, void* data) noexcept {
+    slotdef** pp = (slotdef**)data;
+
+    for (; *pp; pp++)
+        update_one_slot(type, *pp);
+    return 0;
+}
+
+static int update_subclasses(PyTypeObject* type, PyObject* name, update_callback callback, void* data) noexcept;
+static int recurse_down_subclasses(PyTypeObject* type, PyObject* name, update_callback callback, void* data) noexcept;
+
+bool update_slot(BoxedClass* type, const std::string& attr) noexcept {
+    slotdef* ptrs[MAX_EQUIV];
+    slotdef* p;
+    slotdef** pp;
+    int offset;
+
+    /* Clear the VALID_VERSION flag of 'type' and all its
+       subclasses.  This could possibly be unified with the
+       update_subclasses() recursion below, but carefully:
+       they each have their own conditions on which to stop
+       recursing into subclasses. */
+    PyType_Modified(type);
+
+    init_slotdefs();
+    pp = ptrs;
+    for (p = slotdefs; p->name; p++) {
+        /* XXX assume name is interned! */
+        if (p->name == attr)
+            *pp++ = p;
     }
-    return updated;
+    *pp = NULL;
+    for (pp = ptrs; *pp; pp++) {
+        p = *pp;
+        offset = p->offset;
+        while (p > slotdefs && (p - 1)->offset == offset)
+            --p;
+        *pp = p;
+    }
+    if (ptrs[0] == NULL)
+        return false; /* Not an attribute that affects any slots */
+    int r = update_subclasses(type, new BoxedString(attr), update_slots_callback, (void*)ptrs);
+
+    // TODO this is supposed to be a CAPI function!
+    if (r)
+        throwCAPIException();
+    return true;
 }
 
 void fixup_slot_dispatchers(BoxedClass* self) noexcept {
@@ -1483,6 +1556,40 @@ void fixup_slot_dispatchers(BoxedClass* self) noexcept {
         p = update_one_slot(self, p);
 }
 
+static int update_subclasses(PyTypeObject* type, PyObject* name, update_callback callback, void* data) noexcept {
+    if (callback(type, data) < 0)
+        return -1;
+    return recurse_down_subclasses(type, name, callback, data);
+}
+
+static int recurse_down_subclasses(PyTypeObject* type, PyObject* name, update_callback callback, void* data) noexcept {
+    PyTypeObject* subclass;
+    PyObject* ref, *subclasses, *dict;
+    Py_ssize_t i, n;
+
+    subclasses = type->tp_subclasses;
+    if (subclasses == NULL)
+        return 0;
+    assert(PyList_Check(subclasses));
+    n = PyList_GET_SIZE(subclasses);
+    for (i = 0; i < n; i++) {
+        ref = PyList_GET_ITEM(subclasses, i);
+        assert(PyWeakref_CheckRef(ref));
+        subclass = (PyTypeObject*)PyWeakref_GET_OBJECT(ref);
+        assert(subclass != NULL);
+        if ((PyObject*)subclass == Py_None)
+            continue;
+        assert(PyType_Check(subclass));
+        /* Avoid recursing down into unaffected classes */
+        dict = subclass->tp_dict;
+        if (dict != NULL && PyDict_Check(dict) && PyDict_GetItem(dict, name) != NULL)
+            continue;
+        if (update_subclasses(subclass, name, callback, data) < 0)
+            return -1;
+    }
+    return 0;
+}
+
 static PyObject* tp_new_wrapper(PyTypeObject* self, BoxedTuple* args, Box* kwds) noexcept {
     RELEASE_ASSERT(isSubclass(self->cls, type_cls), "");
 
@@ -1509,7 +1616,7 @@ static void add_tp_new_wrapper(BoxedClass* type) noexcept {
                    new BoxedCApiFunction(METH_VARARGS | METH_KEYWORDS, type, "__new__", (PyCFunction)tp_new_wrapper));
 }
 
-static void add_operators(BoxedClass* cls) noexcept {
+void add_operators(BoxedClass* cls) noexcept {
     init_slotdefs();
 
     for (const slotdef& p : slotdefs) {
@@ -2335,6 +2442,52 @@ static void inherit_slots(PyTypeObject* type, PyTypeObject* base) noexcept {
     }
 }
 
+static int add_subclass(PyTypeObject* base, PyTypeObject* type) noexcept {
+    Py_ssize_t i;
+    int result;
+    PyObject* list, *ref, *newobj;
+
+    list = base->tp_subclasses;
+    if (list == NULL) {
+        base->tp_subclasses = list = PyList_New(0);
+        if (list == NULL)
+            return -1;
+    }
+    assert(PyList_Check(list));
+    newobj = PyWeakref_NewRef((PyObject*)type, NULL);
+    i = PyList_GET_SIZE(list);
+    while (--i >= 0) {
+        ref = PyList_GET_ITEM(list, i);
+        assert(PyWeakref_CheckRef(ref));
+        if (PyWeakref_GET_OBJECT(ref) == Py_None)
+            return PyList_SetItem(list, i, newobj);
+    }
+    result = PyList_Append(list, newobj);
+    Py_DECREF(newobj);
+    return result;
+}
+
+static void remove_subclass(PyTypeObject* base, PyTypeObject* type) noexcept {
+    Py_ssize_t i;
+    PyObject* list, *ref;
+
+    list = base->tp_subclasses;
+    if (list == NULL) {
+        return;
+    }
+    assert(PyList_Check(list));
+    i = PyList_GET_SIZE(list);
+    while (--i >= 0) {
+        ref = PyList_GET_ITEM(list, i);
+        assert(PyWeakref_CheckRef(ref));
+        if (PyWeakref_GET_OBJECT(ref) == (PyObject*)type) {
+            /* this can't fail, right? */
+            PySequence_DelItem(list, i);
+            return;
+        }
+    }
+}
+
 // commonClassSetup is for the common code between PyType_Ready (which is just for extension classes)
 // and our internal type-creation endpoints (BoxedClass::BoxedClass()).
 // TODO: Move more of the duplicated logic into here.
@@ -2346,6 +2499,12 @@ void commonClassSetup(BoxedClass* cls) {
             cls->tp_bases = new BoxedTuple({});
     }
 
+    /* Link into each base class's list of subclasses */
+    for (PyObject* b : static_cast<BoxedTuple*>(cls->tp_bases)->elts) {
+        if (PyType_Check(b) && add_subclass((PyTypeObject*)b, cls) < 0)
+            throwCAPIException();
+    }
+
     /* Calculate method resolution order */
     if (mro_internal(cls) < 0)
         throwCAPIException();

src/capi/typeobject.h

@@ -22,6 +22,7 @@ namespace pyston {
 // Returns if a slot was updated
 bool update_slot(BoxedClass* self, const std::string& attr) noexcept;
 
+void add_operators(BoxedClass* self) noexcept;
 void fixup_slot_dispatchers(BoxedClass* self) noexcept;
 void commonClassSetup(BoxedClass* cls);
 

src/capi/types.h

@@ -98,6 +98,7 @@ public:
     DEFAULT_CLASS(wrapperdescr_cls);
 
     static Box* __get__(BoxedWrapperDescriptor* self, Box* inst, Box* owner);
+    static Box* __call__(BoxedWrapperDescriptor* descr, PyObject* self, BoxedTuple* args, Box** _args);
 };
 
 class BoxedWrapperObject : public Box {

src/runtime/bool.cpp

@@ -93,12 +93,6 @@ void setupBool() {
     bool_cls->giveAttr("__xor__", new BoxedFunction(boxRTFunction((void*)boolXor, BOXED_BOOL, 2)));
 
     bool_cls->freeze();
-
-    True = new BoxedBool(true);
-    False = new BoxedBool(false);
-
-    gc::registerPermanentRoot(True);
-    gc::registerPermanentRoot(False);
 }
 
 void teardownBool() {

src/runtime/builtin_modules/sys.cpp

@@ -194,6 +194,7 @@ public:
 
     BoxedSysFlags() {
         auto zero = boxInt(0);
+        assert(zero);
         division_warning = zero;
         bytes_warning = zero;
         no_user_site = zero;
@@ -297,8 +298,8 @@ void setupSys() {
 
     sys_module->giveAttr("maxint", boxInt(PYSTON_INT_MAX));
 
-    sys_flags_cls = BoxedHeapClass::create(type_cls, object_cls, BoxedSysFlags::gcHandler, 0, 0, sizeof(BoxedSysFlags),
-                                           false, "flags");
+    sys_flags_cls = new BoxedHeapClass(object_cls, BoxedSysFlags::gcHandler, 0, 0, sizeof(BoxedSysFlags), false,
+                                       new BoxedString("flags"));
     sys_flags_cls->giveAttr("__new__",
                             new BoxedFunction(boxRTFunction((void*)BoxedSysFlags::__new__, UNKNOWN, 1, 0, true, true)));
 #define ADD(name)                                                                                                      \
@@ -309,6 +310,7 @@ void setupSys() {
     ADD(no_user_site);
 #undef ADD
 
+    sys_flags_cls->tp_mro = new BoxedTuple({ sys_flags_cls, object_cls });
     sys_flags_cls->freeze();
 
     sys_module->giveAttr("flags", new BoxedSysFlags());
@@ -324,5 +326,6 @@ void setupSysEnd() {
                                                               PyLt());
 
     sys_module->giveAttr("builtin_module_names", new BoxedTuple(std::move(builtin_module_names)));
+    sys_flags_cls->finishInitialization();
 }
 }

src/runtime/capi.cpp

@@ -88,6 +88,19 @@ Box* BoxedWrapperDescriptor::__get__(BoxedWrapperDescriptor* self, Box* inst, Bo
     return new BoxedWrapperObject(self, inst);
 }
 
+Box* BoxedWrapperDescriptor::__call__(BoxedWrapperDescriptor* descr, PyObject* self, BoxedTuple* args, Box** _args) {
+    RELEASE_ASSERT(descr->cls == wrapperdescr_cls, "");
+
+    BoxedDict* kw = static_cast<BoxedDict*>(_args[0]);
+
+    if (!isSubclass(self->cls, descr->type))
+        raiseExcHelper(TypeError, "descriptor '' requires a '%s' object but received a '%s'",
+                       getFullNameOfClass(descr->type).c_str(), getFullTypeName(self).c_str());
+
+    auto wrapper = new BoxedWrapperObject(descr, self);
+    return BoxedWrapperObject::__call__(wrapper, args, kw);
+}
+
 extern "C" void _PyErr_BadInternalCall(const char* filename, int lineno) noexcept {
     Py_FatalError("unimplemented");
 }
@@ -264,12 +277,11 @@ extern "C" PyObject* PyObject_GetAttr(PyObject* o, PyObject* attr_name) noexcept
 }
 
 extern "C" PyObject* PyObject_GenericGetAttr(PyObject* o, PyObject* name) noexcept {
-    try {
-        return getattr(o, static_cast<BoxedString*>(name)->s.c_str());
-    } catch (ExcInfo e) {
-        setCAPIException(e);
-        return NULL;
-    }
+    Box* r = getattrInternalGeneric(o, static_cast<BoxedString*>(name)->s.c_str(), NULL, false, false, NULL, NULL);
+    if (!r)
+        PyErr_Format(PyExc_AttributeError, "'%.50s' object has no attribute '%.400s'", o->cls->tp_name,
+                     PyString_AS_STRING(name));
+    return r;
 }
 
 extern "C" PyObject* _PyObject_GenericGetAttrWithDict(PyObject* obj, PyObject* name, PyObject* dict) noexcept {
@@ -1279,9 +1291,6 @@ static Box* methodGetDoc(Box* b, void*) {
 }
 
 void setupCAPI() {
-    capifunc_cls
-        = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedCApiFunction), false, "capifunc");
-
     capifunc_cls->giveAttr("__repr__",
                            new BoxedFunction(boxRTFunction((void*)BoxedCApiFunction::__repr__, UNKNOWN, 1)));
 
@@ -1291,8 +1300,6 @@ void setupCAPI() {
 
     capifunc_cls->freeze();
 
-    method_cls
-        = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedMethodDescriptor), false, "method");
     method_cls->giveAttr("__get__",
                          new BoxedFunction(boxRTFunction((void*)BoxedMethodDescriptor::__get__, UNKNOWN, 3)));
     method_cls->giveAttr("__call__", new BoxedFunction(boxRTFunction((void*)BoxedMethodDescriptor::__call__, UNKNOWN, 2,
@@ -1300,14 +1307,12 @@ void setupCAPI() {
     method_cls->giveAttr("__doc__", new (pyston_getset_cls) BoxedGetsetDescriptor(methodGetDoc, NULL, NULL));
     method_cls->freeze();
 
-    wrapperdescr_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedWrapperDescriptor), false,
-                                              "wrapper_descriptor");
     wrapperdescr_cls->giveAttr("__get__",
                                new BoxedFunction(boxRTFunction((void*)BoxedWrapperDescriptor::__get__, UNKNOWN, 3)));
+    wrapperdescr_cls->giveAttr("__call__", new BoxedFunction(boxRTFunction((void*)BoxedWrapperDescriptor::__call__,
+                                                                           UNKNOWN, 2, 0, true, true)));
     wrapperdescr_cls->freeze();
 
-    wrapperobject_cls
-        = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedWrapperObject), false, "method-wrapper");
     wrapperobject_cls->giveAttr(
         "__call__", new BoxedFunction(boxRTFunction((void*)BoxedWrapperObject::__call__, UNKNOWN, 1, 0, true, true)));
     wrapperobject_cls->freeze();

src/runtime/objmodel.cpp

@@ -1103,10 +1103,39 @@ Box* dataDescriptorInstanceSpecialCases(GetattrRewriteArgs* rewrite_args, const
     return NULL;
 }
 
-inline Box* getclsattr_internal(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args) {
-    return getattrInternalGeneral(obj, attr, rewrite_args,
-                                  /* cls_only */ true,
-                                  /* for_call */ false, NULL, NULL);
+Box* getattrInternalEx(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args, bool cls_only,
+                       bool for_call, Box** bind_obj_out, RewriterVar** r_bind_obj_out) {
+    if (!cls_only) {
+        BoxedClass* cls = obj->cls;
+        if (obj->cls->tp_getattro && obj->cls->tp_getattro != PyObject_GenericGetAttr) {
+            Box* r = obj->cls->tp_getattro(obj, new BoxedString(attr));
+            if (!r)
+                throwCAPIException();
+            return r;
+        }
+
+        if (obj->cls->tp_getattr) {
+            Box* r = obj->cls->tp_getattr(obj, const_cast<char*>(attr.c_str()));
+            if (!r)
+                throwCAPIException();
+            return r;
+        }
+
+        // We could also use the old invalidation-based approach here:
+        if (rewrite_args) {
+            auto r_cls = rewrite_args->obj->getAttr(offsetof(Box, cls));
+            r_cls->addAttrGuard(offsetof(BoxedClass, tp_getattr), (uint64_t)obj->cls->tp_getattr);
+            r_cls->addAttrGuard(offsetof(BoxedClass, tp_getattro), (uint64_t)obj->cls->tp_getattro);
+        }
+    }
+
+    return getattrInternalGeneric(obj, attr, rewrite_args, cls_only, for_call, bind_obj_out, r_bind_obj_out);
+}
+
+inline Box* getclsattrInternal(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args) {
+    return getattrInternalEx(obj, attr, rewrite_args,
+                             /* cls_only */ true,
+                             /* for_call */ false, NULL, NULL);
 }
 
 extern "C" Box* getclsattr(Box* obj, const char* attr) {
@@ -1121,7 +1150,7 @@ extern "C" Box* getclsattr(Box* obj, const char* attr) {
     if (rewriter.get()) {
         //rewriter->trap();
         GetattrRewriteArgs rewrite_args(rewriter.get(), rewriter->getArg(0));
-        gotten = getclsattr_internal(obj, attr, &rewrite_args, NULL);
+        gotten = getclsattrInternal(obj, attr, &rewrite_args, NULL);
 
         if (rewrite_args.out_success && gotten) {
             rewrite_args.out_rtn.move(-1);
@@ -1134,7 +1163,7 @@ extern "C" Box* getclsattr(Box* obj, const char* attr) {
     if (rewriter.get()) {
         // rewriter->trap();
         GetattrRewriteArgs rewrite_args(rewriter.get(), rewriter->getArg(0), rewriter->getReturnDestination());
-        gotten = getclsattr_internal(obj, attr, &rewrite_args);
+        gotten = getclsattrInternal(obj, attr, &rewrite_args);
 
         if (rewrite_args.out_success && gotten) {
             rewriter->commitReturning(rewrite_args.out_rtn);
@@ -1142,7 +1171,7 @@ extern "C" Box* getclsattr(Box* obj, const char* attr) {
 #endif
 }
 else {
-    gotten = getclsattr_internal(obj, attr, NULL);
+    gotten = getclsattrInternal(obj, attr, NULL);
 }
 RELEASE_ASSERT(gotten, "%s:%s", getTypeName(obj), attr);
 
@@ -1173,12 +1202,13 @@ static Box* (*runtimeCall2)(Box*, ArgPassSpec, Box*, Box*) = (Box * (*)(Box*, Ar
 static Box* (*runtimeCall3)(Box*, ArgPassSpec, Box*, Box*, Box*)
     = (Box * (*)(Box*, ArgPassSpec, Box*, Box*, Box*))runtimeCall;
 
-Box* getattrInternalGeneral(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args, bool cls_only,
+Box* getattrInternalGeneric(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args, bool cls_only,
                             bool for_call, Box** bind_obj_out, RewriterVar** r_bind_obj_out) {
     if (for_call) {
         *bind_obj_out = NULL;
     }
 
+    // TODO this should be a custom getattr
     if (obj->cls == closure_cls) {
         Box* val = NULL;
         if (rewrite_args) {
@@ -1213,23 +1243,6 @@ Box* getattrInternalGeneral(Box* obj, const std::string& attr, GetattrRewriteArg
         raiseExcHelper(NameError, "free variable '%s' referenced before assignment in enclosing scope", attr.c_str());
     }
 
-    if (!cls_only) {
-        // Don't need to pass icentry args, since we special-case __getattribtue__ and __getattr__ to use
-        // invalidation rather than guards
-        // TODO since you changed this to typeLookup you need to guard
-        Box* getattribute = typeLookup(obj->cls, getattribute_str, NULL);
-        if (getattribute) {
-            // TODO this is a good candidate for interning?
-            Box* boxstr = boxString(attr);
-            Box* rtn = runtimeCall2(getattribute, ArgPassSpec(2), obj, boxstr);
-            return rtn;
-        }
-
-        if (rewrite_args) {
-            rewrite_args->rewriter->addDependenceOn(obj->cls->dependent_icgetattrs);
-        }
-    }
-
     // Handle descriptor logic here.
     // A descriptor is either a data descriptor or a non-data descriptor.
     // data descriptors define both __get__ and __set__. non-data descriptors
@@ -1499,35 +1512,11 @@ Box* getattrInternalGeneral(Box* obj, const std::string& attr, GetattrRewriteArg
     // TODO this shouldn't go here; it should be in instancemethod_cls->tp_getattr[o]
     if (obj->cls == instancemethod_cls) {
         assert(!rewrite_args || !rewrite_args->out_success);
-        return getattrInternalGeneral(static_cast<BoxedInstanceMethod*>(obj)->func, attr, NULL, cls_only, for_call,
-                                      bind_obj_out, NULL);
+        return getattrInternalEx(static_cast<BoxedInstanceMethod*>(obj)->func, attr, NULL, cls_only, for_call,
+                                 bind_obj_out, NULL);
     }
     // Finally, check __getattr__
 
-    if (!cls_only) {
-        // Don't need to pass icentry args, since we special-case __getattribute__ and __getattr__ to use
-        // invalidation rather than guards
-        rewrite_args = NULL;
-        REWRITE_ABORTED("");
-
-        if (obj->cls->tp_getattr) {
-            Box* rtn = obj->cls->tp_getattr(obj, const_cast<char*>(attr.c_str()));
-            if (rtn == NULL)
-                throwCAPIException();
-            return rtn;
-        }
-        Box* getattr = typeLookup(obj->cls, getattr_str, NULL);
-        if (getattr) {
-            Box* boxstr = boxString(attr);
-            Box* rtn = runtimeCall2(getattr, ArgPassSpec(2), obj, boxstr);
-            return rtn;
-        }
-
-        if (rewrite_args) {
-            rewrite_args->rewriter->addDependenceOn(obj->cls->dependent_icgetattrs);
-        }
-    }
-
     if (rewrite_args) {
         rewrite_args->out_success = true;
     }
@@ -1535,9 +1524,9 @@ Box* getattrInternalGeneral(Box* obj, const std::string& attr, GetattrRewriteArg
 }
 
 Box* getattrInternal(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args) {
-    return getattrInternalGeneral(obj, attr, rewrite_args,
-                                  /* cls_only */ false,
-                                  /* for_call */ false, NULL, NULL);
+    return getattrInternalEx(obj, attr, rewrite_args,
+                             /* cls_only */ false,
+                             /* for_call */ false, NULL, NULL);
 }
 
 extern "C" Box* getattr(Box* obj, const char* attr) {
@@ -1878,9 +1867,9 @@ extern "C" bool nonzero(Box* obj) {
     // Stats::log(id);
 
     // go through descriptor logic
-    Box* func = getclsattr_internal(obj, "__nonzero__", NULL);
+    Box* func = getclsattrInternal(obj, "__nonzero__", NULL);
     if (!func)
-        func = getclsattr_internal(obj, "__len__", NULL);
+        func = getclsattrInternal(obj, "__len__", NULL);
 
     if (func == NULL) {
         ASSERT(isUserDefined(obj->cls) || obj->cls == classobj_cls || obj->cls == type_cls
@@ -2001,7 +1990,7 @@ extern "C" BoxedInt* hash(Box* obj) {
     slowpath_hash.log();
 
     // goes through descriptor logic
-    Box* hash = getclsattr_internal(obj, "__hash__", NULL);
+    Box* hash = getclsattrInternal(obj, "__hash__", NULL);
 
     if (hash == NULL) {
         ASSERT(isUserDefined(obj->cls) || obj->cls == function_cls || obj->cls == object_cls || obj->cls == classobj_cls
@@ -2241,20 +2230,20 @@ extern "C" Box* callattrInternal(Box* obj, const std::string* attr, LookupScope
 
     // Look up the argument. Pass in the arguments to getattrInternalGeneral or getclsattr_general
     // that will shortcut functions by not putting them into instancemethods
-    Box* bind_obj;
+    Box* bind_obj = NULL; // Initialize this to NULL to allow getattrInternalEx to ignore it
     RewriterVar* r_bind_obj;
     Box* val;
     RewriterVar* r_val = NULL;
     if (rewrite_args) {
         GetattrRewriteArgs grewrite_args(rewrite_args->rewriter, rewrite_args->obj, Location::any());
-        val = getattrInternalGeneral(obj, *attr, &grewrite_args, scope == CLASS_ONLY, true, &bind_obj, &r_bind_obj);
+        val = getattrInternalEx(obj, *attr, &grewrite_args, scope == CLASS_ONLY, true, &bind_obj, &r_bind_obj);
         if (!grewrite_args.out_success) {
             rewrite_args = NULL;
         } else if (val) {
             r_val = grewrite_args.out_rtn;
         }
     } else {
-        val = getattrInternalGeneral(obj, *attr, NULL, scope == CLASS_ONLY, true, &bind_obj, &r_bind_obj);
+        val = getattrInternalEx(obj, *attr, NULL, scope == CLASS_ONLY, true, &bind_obj, &r_bind_obj);
     }
 
     if (val == NULL) {
@@ -2343,14 +2332,6 @@ extern "C" Box* callattrInternal(Box* obj, const std::string* attr, LookupScope
         }
     } else {
         Box* rtn;
-        // I *think* this check is here to limit the recursion nesting for rewriting, and originates
-        // from a time when we didn't have silent-abort-when-patchpoint-full.
-        if (val->cls != function_cls && val->cls != builtin_function_or_method_cls && val->cls != instancemethod_cls
-            && val->cls != capifunc_cls) {
-            rewrite_args = NULL;
-            REWRITE_ABORTED("");
-        }
-
         if (rewrite_args) {
             CallRewriteArgs srewrite_args(rewrite_args->rewriter, r_val, rewrite_args->destination);
             if (npassed_args >= 1)
@@ -3456,7 +3437,7 @@ extern "C" Box* unaryop(Box* operand, int op_type) {
 
     const std::string& op_name = getOpName(op_type);
 
-    Box* attr_func = getclsattr_internal(operand, op_name, NULL);
+    Box* attr_func = getclsattrInternal(operand, op_name, NULL);
 
     ASSERT(attr_func, "%s.%s", getTypeName(operand), op_name.c_str());
 

src/runtime/objmodel.h

@@ -121,7 +121,7 @@ extern "C" void delattr_internal(Box* obj, const std::string& attr, bool allow_c
 struct CompareRewriteArgs;
 Box* compareInternal(Box* lhs, Box* rhs, int op_type, CompareRewriteArgs* rewrite_args);
 Box* getattrInternal(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args);
-Box* getattrInternalGeneral(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args, bool cls_only,
+Box* getattrInternalGeneric(Box* obj, const std::string& attr, GetattrRewriteArgs* rewrite_args, bool cls_only,
                             bool for_call, Box** bind_obj_out, RewriterVar** r_bind_obj_out);
 
 Box* typeLookup(BoxedClass* cls, const std::string& attr, GetattrRewriteArgs* rewrite_args);

src/runtime/stacktrace.cpp

@@ -144,7 +144,11 @@ extern "C" void abort() {
         // that object, _printStackTrace will hang waiting for the first construction
         // to finish.)
         alarm(1);
-        _printStacktrace();
+        try {
+            _printStacktrace();
+        } catch (ExcInfo) {
+            fprintf(stderr, "error printing stack trace during abort()");
+        }
 
         // Cancel the alarm.
         // This is helpful for when running in a debugger, since the debugger will catch the

src/runtime/types.cpp

@@ -104,7 +104,8 @@ extern "C" PyObject* PystonType_GenericAlloc(BoxedClass* cls, Py_ssize_t nitems)
     }
 #endif
     if (!cls->tp_mro) {
-        assert(!attrwrapper_cls); // the last class to be set up during bootstrapping
+        // wrapperdescr_cls is the last class to be set up during bootstrapping:
+        ASSERT(!wrapperdescr_cls, "looks like we need to set up the mro for %s manually", cls->tp_name);
     } else {
         assert(cls->tp_mro && "maybe we should just skip these checks if !mro");
         assert(cls->tp_mro->cls == tuple_cls);
@@ -432,6 +433,8 @@ extern "C" void typeGCHandler(GCVisitor* v, Box* b) {
         v->visit(cls->tp_mro);
     if (cls->tp_bases)
         v->visit(cls->tp_bases);
+    if (cls->tp_subclasses)
+        v->visit(cls->tp_subclasses);
 
     if (cls->tp_flags & Py_TPFLAGS_HEAPTYPE) {
         BoxedHeapClass* hcls = static_cast<BoxedHeapClass*>(cls);
@@ -1735,6 +1738,36 @@ void setupRuntime() {
         = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedGetsetDescriptor), false, boxStrConstant("getset"));
     attrwrapper_cls = new BoxedHeapClass(object_cls, &AttrWrapper::gcHandler, 0, 0, sizeof(AttrWrapper), false,
                                          new BoxedString("attrwrapper"));
+    dict_cls = new BoxedHeapClass(object_cls, &dictGCHandler, 0, 0, sizeof(BoxedDict), false, new BoxedString("dict"));
+    file_cls = new BoxedHeapClass(object_cls, NULL, 0, offsetof(BoxedFile, weakreflist), sizeof(BoxedFile), false,
+                                  new BoxedString("file"));
+    int_cls = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedInt), false, new BoxedString("int"));
+    bool_cls = new BoxedHeapClass(int_cls, NULL, 0, 0, sizeof(BoxedBool), false, new BoxedString("bool"));
+    complex_cls = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedComplex), false, new BoxedString("complex"));
+    long_cls = new BoxedHeapClass(object_cls, &BoxedLong::gchandler, 0, 0, sizeof(BoxedLong), false,
+                                  new BoxedString("long"));
+    float_cls = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedFloat), false, new BoxedString("float"));
+    function_cls = new BoxedHeapClass(object_cls, &functionGCHandler, offsetof(BoxedFunction, attrs),
+                                      offsetof(BoxedFunction, in_weakreflist), sizeof(BoxedFunction), false,
+                                      new BoxedString("function"));
+    builtin_function_or_method_cls = new BoxedHeapClass(
+        object_cls, &functionGCHandler, 0, offsetof(BoxedBuiltinFunctionOrMethod, in_weakreflist),
+        sizeof(BoxedBuiltinFunctionOrMethod), false, new BoxedString("builtin_function_or_method"));
+    function_cls->simple_destructor = builtin_function_or_method_cls->simple_destructor = functionDtor;
+
+
+    module_cls = new BoxedHeapClass(object_cls, NULL, offsetof(BoxedModule, attrs), 0, sizeof(BoxedModule), false,
+                                    new BoxedString("module"));
+    member_cls
+        = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedMemberDescriptor), false, new BoxedString("member"));
+    capifunc_cls
+        = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedCApiFunction), false, new BoxedString("capifunc"));
+    method_cls
+        = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedMethodDescriptor), false, new BoxedString("method"));
+    wrapperobject_cls = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedWrapperObject), false,
+                                           new BoxedString("method-wrapper"));
+    wrapperdescr_cls = new BoxedHeapClass(object_cls, NULL, 0, 0, sizeof(BoxedWrapperDescriptor), false,
+                                          new BoxedString("wrapper_descriptor"));
 
 
     // Kind of hacky, but it's easier to manually construct the mro for a couple key classes
@@ -1746,6 +1779,47 @@ void setupRuntime() {
     type_cls->tp_mro = new BoxedTuple({ type_cls, object_cls });
     pyston_getset_cls->tp_mro = new BoxedTuple({ pyston_getset_cls, object_cls });
     attrwrapper_cls->tp_mro = new BoxedTuple({ attrwrapper_cls, object_cls });
+    dict_cls->tp_mro = new BoxedTuple({ dict_cls, object_cls });
+    file_cls->tp_mro = new BoxedTuple({ file_cls, object_cls });
+    int_cls->tp_mro = new BoxedTuple({ int_cls, object_cls });
+    bool_cls->tp_mro = new BoxedTuple({ bool_cls, object_cls });
+    complex_cls->tp_mro = new BoxedTuple({ complex_cls, object_cls });
+    long_cls->tp_mro = new BoxedTuple({ long_cls, object_cls });
+    float_cls->tp_mro = new BoxedTuple({ float_cls, object_cls });
+    function_cls->tp_mro = new BoxedTuple({ function_cls, object_cls });
+    builtin_function_or_method_cls->tp_mro = new BoxedTuple({ builtin_function_or_method_cls, object_cls });
+    member_cls->tp_mro = new BoxedTuple({ member_cls, object_cls });
+    capifunc_cls->tp_mro = new BoxedTuple({ capifunc_cls, object_cls });
+    module_cls->tp_mro = new BoxedTuple({ module_cls, object_cls });
+    method_cls->tp_mro = new BoxedTuple({ method_cls, object_cls });
+    wrapperobject_cls->tp_mro = new BoxedTuple({ wrapperobject_cls, object_cls });
+    wrapperdescr_cls->tp_mro = new BoxedTuple({ wrapperdescr_cls, object_cls });
+
+    STR = typeFromClass(str_cls);
+    BOXED_INT = typeFromClass(int_cls);
+    BOXED_FLOAT = typeFromClass(float_cls);
+    BOXED_BOOL = typeFromClass(bool_cls);
+    NONE = typeFromClass(none_cls);
+    LIST = typeFromClass(list_cls);
+    MODULE = typeFromClass(module_cls);
+    DICT = typeFromClass(dict_cls);
+    BOXED_TUPLE = typeFromClass(tuple_cls);
+    LONG = typeFromClass(long_cls);
+    BOXED_COMPLEX = typeFromClass(complex_cls);
+
+    True = new BoxedBool(true);
+    False = new BoxedBool(false);
+
+    gc::registerPermanentRoot(True);
+    gc::registerPermanentRoot(False);
+
+    // Need to initialize interned_ints early:
+    setupInt();
+    // sys is the first module that needs to be set up, due to modules
+    // being tracked in sys.modules:
+    setupSys();
+    // Weakrefs are used for tp_subclasses:
+    init_weakref();
 
     object_cls->finishInitialization();
     type_cls->finishInitialization();
@@ -1756,6 +1830,24 @@ void setupRuntime() {
     list_cls->finishInitialization();
     pyston_getset_cls->finishInitialization();
     attrwrapper_cls->finishInitialization();
+    dict_cls->finishInitialization();
+    file_cls->finishInitialization();
+    int_cls->finishInitialization();
+    bool_cls->finishInitialization();
+    complex_cls->finishInitialization();
+    long_cls->finishInitialization();
+    float_cls->finishInitialization();
+    function_cls->finishInitialization();
+    builtin_function_or_method_cls->finishInitialization();
+    member_cls->finishInitialization();
+    module_cls->finishInitialization();
+    capifunc_cls->finishInitialization();
+    method_cls->finishInitialization();
+    wrapperobject_cls->finishInitialization();
+    wrapperdescr_cls->finishInitialization();
+
+    object_cls->tp_getattro = PyObject_GenericGetAttr;
+    add_operators(object_cls);
 
     str_cls->tp_flags |= Py_TPFLAGS_HAVE_NEWBUFFER;
 
@@ -1764,42 +1856,15 @@ void setupRuntime() {
     type_cls->giveAttr("__dict__", dict_descr);
 
 
-    module_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, offsetof(BoxedModule, attrs), 0,
-                                        sizeof(BoxedModule), false, "module");
-
-    // TODO it'd be nice to be able to do these in the respective setupType methods,
-    // but those setup methods probably want access to these objects.
-    // We could have a multi-stage setup process, but that seems overkill for now.
-    int_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedInt), false, "int");
-    bool_cls = BoxedHeapClass::create(type_cls, int_cls, NULL, 0, 0, sizeof(BoxedBool), false, "bool");
-    complex_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedComplex), false, "complex");
-    long_cls
-        = BoxedHeapClass::create(type_cls, object_cls, &BoxedLong::gchandler, 0, 0, sizeof(BoxedLong), false, "long");
-    float_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedFloat), false, "float");
-    function_cls
-        = BoxedHeapClass::create(type_cls, object_cls, &functionGCHandler, offsetof(BoxedFunction, attrs),
-                                 offsetof(BoxedFunction, in_weakreflist), sizeof(BoxedFunction), false, "function");
-
-    builtin_function_or_method_cls = BoxedHeapClass::create(
-        type_cls, object_cls, &functionGCHandler, 0, offsetof(BoxedBuiltinFunctionOrMethod, in_weakreflist),
-        sizeof(BoxedBuiltinFunctionOrMethod), false, "builtin_function_or_method");
-    function_cls->simple_destructor = builtin_function_or_method_cls->simple_destructor = functionDtor;
-
     instancemethod_cls = BoxedHeapClass::create(type_cls, object_cls, &instancemethodGCHandler, 0,
                                                 offsetof(BoxedInstanceMethod, in_weakreflist),
                                                 sizeof(BoxedInstanceMethod), false, "instancemethod");
 
-    list_cls = BoxedHeapClass::create(type_cls, object_cls, &listGCHandler, 0, 0, sizeof(BoxedList), false, "list");
     slice_cls = BoxedHeapClass::create(type_cls, object_cls, &sliceGCHandler, 0, 0, sizeof(BoxedSlice), false, "slice");
-    dict_cls = BoxedHeapClass::create(type_cls, object_cls, &dictGCHandler, 0, 0, sizeof(BoxedDict), false, "dict");
-    file_cls = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, offsetof(BoxedFile, weakreflist),
-                                      sizeof(BoxedFile), false, "file");
     set_cls = BoxedHeapClass::create(type_cls, object_cls, &setGCHandler, 0, offsetof(BoxedSet, weakreflist),
                                      sizeof(BoxedSet), false, "set");
     frozenset_cls = BoxedHeapClass::create(type_cls, object_cls, &setGCHandler, 0, offsetof(BoxedSet, weakreflist),
                                            sizeof(BoxedSet), false, "frozenset");
-    member_cls
-        = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedMemberDescriptor), false, "member");
     capi_getset_cls
         = BoxedHeapClass::create(type_cls, object_cls, NULL, 0, 0, sizeof(BoxedGetsetDescriptor), false, "getset");
     closure_cls = BoxedHeapClass::create(type_cls, object_cls, &closureGCHandler, offsetof(BoxedClosure, attrs), 0,
@@ -1817,20 +1882,9 @@ void setupRuntime() {
     pyston_getset_cls->freeze();
     capi_getset_cls->freeze();
 
-    STR = typeFromClass(str_cls);
-    BOXED_INT = typeFromClass(int_cls);
-    BOXED_FLOAT = typeFromClass(float_cls);
-    BOXED_BOOL = typeFromClass(bool_cls);
-    NONE = typeFromClass(none_cls);
-    LIST = typeFromClass(list_cls);
     SLICE = typeFromClass(slice_cls);
-    MODULE = typeFromClass(module_cls);
-    DICT = typeFromClass(dict_cls);
     SET = typeFromClass(set_cls);
     FROZENSET = typeFromClass(frozenset_cls);
-    BOXED_TUPLE = typeFromClass(tuple_cls);
-    LONG = typeFromClass(long_cls);
-    BOXED_COMPLEX = typeFromClass(complex_cls);
 
     object_cls->giveAttr("__new__", new BoxedFunction(boxRTFunction((void*)objectNew, UNKNOWN, 1, 0, true, true)));
     object_cls->giveAttr("__init__", new BoxedFunction(boxRTFunction((void*)objectInit, UNKNOWN, 1, 0, true, false)));
@@ -1878,7 +1932,6 @@ void setupRuntime() {
     object_cls->freeze();
 
     setupBool();
-    setupInt();
     setupLong();
     setupFloat();
     setupComplex();
@@ -1970,10 +2023,6 @@ void setupRuntime() {
     attrwrapperiter_cls->giveAttr("next", new BoxedFunction(boxRTFunction((void*)AttrWrapperIter::next, UNKNOWN, 1)));
     attrwrapperiter_cls->freeze();
 
-    // sys is the first module that needs to be set up, due to modules
-    // being tracked in sys.modules:
-    setupSys();
-
     setupBuiltins();
     _PyExc_Init();
     setupThread();
@@ -2012,7 +2061,6 @@ void setupRuntime() {
     init_codecs();
     init_socket();
     initunicodedata();
-    init_weakref();
     initcStringIO();
     init_io();
     initzipimport();

src/runtime/types.h

@@ -204,6 +204,7 @@ protected:
                bool is_user_defined);
 
     friend void setupRuntime();
+    friend void setupSysEnd();
 };
 
 class BoxedHeapClass : public BoxedClass {
@@ -232,6 +233,7 @@ private:
                    bool is_user_defined, BoxedString* name);
 
     friend void setupRuntime();
+    friend void setupSys();
 
     DEFAULT_CLASS(type_cls);
 };

test/tests/55.py

-# expected: fail
-# - object.__getattribute__ doesn't exist
-
 # attr-getting resolution.
 
 class M(type):

test/tests/descriptors_double.py

@@ -53,8 +53,6 @@ else:
     print 'False'
 
 # __getattr__ and __setattr__
-# Looks like __getattr__ and __setattr__ should *not* be looked up with
-# the descriptor protocol
 class DescriptorGetattr(object):
     def __get__(self, obj, type):
         print 'getattr __get__ called'
@@ -68,8 +66,8 @@ class DescriptorSetattr(object):
         def setattr(attr, val):
             print 'setattr called for attr', attr, val
 class D(object):
-    __getattr__ = DescriptorGetattr
-    __setattr__ = DescriptorSetattr
+    __getattr__ = DescriptorGetattr()
+    __setattr__ = DescriptorSetattr()
 
 d = D()
 try:

test/tests/object_default_behavior.py

@@ -6,8 +6,15 @@ class C(object):
         else:
             object.__setattr__(self, attr, value)
 
+    def __getattribute__(self, attr):
+        print "getattribute", attr
+        if attr.startswith("c"):
+            return "yum"
+        return object.__getattribute__(self, attr)
+
 c = C()
 c.a = 1
 c.b = 2
 c.c = 3
 print sorted(c.__dict__.items())
+print c.a, c.b, c.c