Implement LOAD_ATTR/py.GetAttr

Author: ncw

py/internal.go

@@ -98,3 +98,53 @@ func SetItem(self Object, key Object, value Object) Object {
 	// FIXME should be TypeError
 	panic(fmt.Sprintf("TypeError: '%s' object does not support item assignment", self.Type().Name))
 }
+
+// GetAttrOrNil - returns the result nil if attribute not found
+func GetAttrOrNil(self Object, key string) Object {
+	// Call __getattribute unconditionally if it exists
+	if I, ok := self.(I__getattribute__); ok {
+		return I.M__getattribute__(Object(String(key)))
+	} else if res, ok := TypeCall1(self, "__getattribute__", Object(String(key))); ok {
+		// FIXME catch AttributeError here
+		return res
+	}
+
+	if t, ok := self.(*Type); ok {
+		// Now look in the instance dictionary etc
+		res := t.GetAttrOrNil(key)
+		if res != nil {
+			return res
+		}
+	} else {
+		// FIXME introspection for M__methods__ on non *Type objects
+	}
+
+	// And now only if not found call __getattr__
+	if I, ok := self.(I__getattr__); ok {
+		return I.M__getattr__(Object(String(key)))
+	} else if res, ok := TypeCall1(self, "__getitem__", Object(String(key))); ok {
+		return res
+	}
+
+	// Not found - return nil
+	return nil
+}
+
+// GetAttrString
+func GetAttrString(self Object, key string) Object {
+	res := GetAttrOrNil(self, key)
+	if res == nil {
+		// FIXME should be AttributeError
+		panic(fmt.Sprintf("AttributeError: '%s' has no attribute '%s'", self.Type().Name, key))
+	}
+	return res
+}
+
+// GetAttr
+func GetAttr(self Object, keyObj Object) Object {
+	if key, ok := keyObj.(String); ok {
+		return GetAttrString(self, string(key))
+	}
+	// FIXME should be TypeError
+	panic(fmt.Sprintf("TypeError: attribute name must be string, not '%s'", self.Type().Name))
+}

py/type.go

@@ -324,10 +324,14 @@ func (t *Type) Lookup(name string) Object {
 
 // Get an attribute from the type
 //
+// Doesn't call __getattr__ etc
+//
+// Returns nil if not found
+//
 // FIXME this isn't totally correct!
 // as we are ignoring getattribute etc
 // See _PyObject_GenericGetAttrWithDict in object.c
-func (t *Type) GetMethod(name string) Object {
+func (t *Type) GetAttrOrNil(name string) Object {
 	// Look in instance dictionary first
 	if res, ok := t.Dict[name]; ok {
 		return res
@@ -336,6 +340,7 @@ func (t *Type) GetMethod(name string) Object {
 	if res, ok := t.Type().Dict[name]; ok {
 		return res
 	}
+	// Now look through base classes etc
 	return t.Lookup(name)
 }
 
@@ -347,7 +352,7 @@ func (t *Type) GetMethod(name string) Object {
 //
 // May raise exceptions if calling the method failed
 func (t *Type) CallMethod(name string, args Tuple, kwargs StringDict) (Object, bool) {
-	fn := t.GetMethod(name)
+	fn := t.GetAttrOrNil(name) // FIXME this should use py.GetAttrOrNil?
 	if fn == nil {
 		return nil, false
 	}

vm/eval.go

@@ -557,7 +557,7 @@ func do_BUILD_MAP(vm *Vm, count int32) {
 
 // Replaces TOS with getattr(TOS, co_names[namei]).
 func do_LOAD_ATTR(vm *Vm, namei int32) {
-	vm.NotImplemented("LOAD_ATTR", namei)
+	vm.SET_TOP(py.GetAttrString(vm.TOP(), vm.frame.Code.Names[namei]))
 }
 
 // Performs a Boolean operation. The operation name can be found in