(oldstyle) instance.nonzero

src/runtime/classobj.cpp

@@ -154,7 +154,7 @@ Box* classobjStr(Box* _obj) {
     return boxString(static_cast<BoxedString*>(_mod)->s + "." + cls->name->s);
 }
 
-Box* instanceGetattribute(Box* _inst, Box* _attr) {
+static Box* _instanceGetattribute(Box* _inst, Box* _attr, bool raise_on_missing) {
     RELEASE_ASSERT(_inst->cls == instance_cls, "");
     BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);
 
@@ -177,15 +177,22 @@ Box* instanceGetattribute(Box* _inst, Box* _attr) {
     Box* getattr = classLookup(inst->inst_cls, getattr_str);
     RELEASE_ASSERT(getattr == NULL, "unimplemented");
 
+    if (!raise_on_missing)
+        return NULL;
+
     raiseExcHelper(AttributeError, "%s instance has no attribute '%s'", inst->inst_cls->name->s.c_str(),
                    attr->s.c_str());
 }
 
+Box* instanceGetattribute(Box* _inst, Box* _attr) {
+    return _instanceGetattribute(_inst, _attr, true);
+}
+
 Box* instanceStr(Box* _inst) {
     RELEASE_ASSERT(_inst->cls == instance_cls, "");
     BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);
 
-    Box* str_func = instanceGetattribute(inst, boxStrConstant("__str__"));
+    Box* str_func = _instanceGetattribute(inst, boxStrConstant("__str__"), false);
 
     if (str_func) {
         return runtimeCall(str_func, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
@@ -194,6 +201,19 @@ Box* instanceStr(Box* _inst) {
     }
 }
 
+Box* instanceNonzero(Box* _inst) {
+    RELEASE_ASSERT(_inst->cls == instance_cls, "");
+    BoxedInstance* inst = static_cast<BoxedInstance*>(_inst);
+
+    Box* nonzero_func = _instanceGetattribute(inst, boxStrConstant("__nonzero__"), false);
+
+    if (nonzero_func) {
+        return runtimeCall(nonzero_func, ArgPassSpec(0), NULL, NULL, NULL, NULL, NULL);
+    } else {
+        return True;
+    }
+}
+
 void setupClassobj() {
     classobj_cls = new BoxedClass(type_cls, object_cls, &BoxedClassobj::gcHandler, offsetof(BoxedClassobj, attrs),
                                   sizeof(BoxedClassobj), false);
@@ -218,6 +238,7 @@ void setupClassobj() {
     instance_cls->giveAttr("__getattribute__",
                            new BoxedFunction(boxRTFunction((void*)instanceGetattribute, UNKNOWN, 2)));
     instance_cls->giveAttr("__str__", new BoxedFunction(boxRTFunction((void*)instanceStr, UNKNOWN, 1)));
+    instance_cls->giveAttr("__nonzero__", new BoxedFunction(boxRTFunction((void*)instanceNonzero, UNKNOWN, 1)));
 
     instance_cls->freeze();
 }

src/runtime/objmodel.cpp

@@ -38,6 +38,7 @@
 #include "gc/collector.h"
 #include "gc/heap.h"
 #include "runtime/capi.h"
+#include "runtime/classobj.h"
 #include "runtime/float.h"
 #include "runtime/generator.h"
 #include "runtime/iterobject.h"
@@ -1547,7 +1548,8 @@ extern "C" bool nonzero(Box* obj) {
     Box* func = getclsattr_internal(obj, "__nonzero__", NULL);
 
     if (func == NULL) {
-        RELEASE_ASSERT(isUserDefined(obj->cls), "%s.__nonzero__", getTypeName(obj)->c_str()); // TODO
+        ASSERT(isUserDefined(obj->cls) || obj->cls == classobj_cls, "%s.__nonzero__",
+               getTypeName(obj)->c_str()); // TODO
         return true;
     }
 

test/tests/oldstyle_classes.py

@@ -53,3 +53,16 @@ def str2():
     return "str2"
 e.__str__ = str2
 print e
+
+print bool(e)
+print bool(E)
+
+class F:
+    def __init__(self, n):
+        self.n = n
+
+    def __nonzero__(self):
+        return self.n
+
+print bool(F(0))
+print bool(F(1))