Merge pull request #138 from mappu/miqt-subclass

Remove isSubclass

cmd/genbindings/emitcabi.go

@@ -749,14 +749,14 @@ extern "C" {
 		}
 
 		for _, m := range c.VirtualMethods() {
-			ret.WriteString(fmt.Sprintf("void %s_override_virtual_%s(%s* self, intptr_t slot);\n", methodPrefixName, m.SafeMethodName(), "void" /*methodPrefixName*/))
+			ret.WriteString(fmt.Sprintf("bool %s_override_virtual_%s(%s* self, intptr_t slot);\n", methodPrefixName, m.SafeMethodName(), "void" /*methodPrefixName*/))
 
 			ret.WriteString(fmt.Sprintf("%s %s_virtualbase_%s(%s);\n", m.ReturnType.RenderTypeCabi(), methodPrefixName, m.SafeMethodName(), emitParametersCabi(m, ifv(m.IsConst, "const ", "")+"void" /*methodPrefixName*/ +"*")))
 		}
 
 		// delete
 		if c.CanDelete {
-			ret.WriteString(fmt.Sprintf("void %s_Delete(%s* self, bool isSubclass);\n", methodPrefixName, methodPrefixName))
+			ret.WriteString(fmt.Sprintf("void %s_Delete(%s* self);\n", methodPrefixName, methodPrefixName))
 		}
 
 		ret.WriteString("\n")
@@ -865,7 +865,7 @@ extern "C" {
 
 			overriddenClassName := "MiqtVirtual" + strings.Replace(cppClassName, `::`, ``, -1)
 
-			ret.WriteString("class " + overriddenClassName + " : public virtual " + cppClassName + " {\n" +
+			ret.WriteString("class " + overriddenClassName + " final : public " + cppClassName + " {\n" +
 				"public:\n" +
 				"\n",
 			)
@@ -885,7 +885,7 @@ extern "C" {
 				)
 			} else {
 				ret.WriteString(
-					"\tvirtual ~" + overriddenClassName + "() = default;\n" +
+					"\tvirtual ~" + overriddenClassName + "() override = default;\n" +
 						"\n",
 				)
 			}
@@ -1178,8 +1178,14 @@ extern "C" {
 			// upclass it
 
 			ret.WriteString(
-				`void ` + methodPrefixName + `_override_virtual_` + m.SafeMethodName() + `(void* self, intptr_t slot) {` + "\n" +
-					"\tdynamic_cast<" + cppClassName + "*>( (" + cabiClassName(c.ClassName) + "*)(self) )->handle__" + m.SafeMethodName() + " = slot;\n" +
+				`bool ` + methodPrefixName + `_override_virtual_` + m.SafeMethodName() + `(void* self, intptr_t slot) {` + "\n" +
+					"\t" + cppClassName + "* self_cast = dynamic_cast<" + cppClassName + "*>( (" + cabiClassName(c.ClassName) + "*)(self) );\n" +
+					"\tif (self_cast == nullptr) {\n" +
+					"\t\treturn false;\n" +
+					"\t}\n" +
+					"\t\n" +
+					"\tself_cast->handle__" + m.SafeMethodName() + " = slot;\n" +
+					"\treturn true;\n" +
 					"}\n" +
 					"\n",
 			)
@@ -1217,14 +1223,12 @@ extern "C" {
 		}
 
 		// Delete
+		// If we subclassed, our class destructor is always virtual. Therefore
+		// we can delete from the self ptr without any dynamic_cast<>
 		if c.CanDelete {
 			ret.WriteString(
-				"void " + methodPrefixName + "_Delete(" + methodPrefixName + "* self, bool isSubclass) {\n" +
-					"\tif (isSubclass) {\n" +
-					"\t\tdelete dynamic_cast<" + cppClassName + "*>( self );\n" +
-					"\t} else {\n" +
-					"\t\tdelete self;\n" +
-					"\t}\n" +
+				"void " + methodPrefixName + "_Delete(" + methodPrefixName + "* self) {\n" +
+					"\tdelete self;\n" +
 					"}\n" +
 					"\n",
 			)

cmd/genbindings/emitgo.go

@@ -767,7 +767,6 @@ import "C"
 		ret.WriteString(`
 		type ` + goClassName + ` struct {
 			h *C.` + goClassName + `
-			isSubclass bool
 		`)
 
 		// Embed all inherited types to directly allow calling inherited methods
@@ -886,9 +885,7 @@ import "C"
 			// Call Cgo constructor
 
 			ret.WriteString(`				
-				ret := new` + goClassName + `(C.` + goClassName + `_new` + maybeSuffix(i) + `(` + forwarding + `))
-				ret.isSubclass = true
-				return ret
+				return new` + goClassName + `(C.` + goClassName + `_new` + maybeSuffix(i) + `(` + forwarding + `))
 			}
 			
 			`)
@@ -1035,10 +1032,10 @@ import "C"
 				goCbType += `) ` + m.ReturnType.renderReturnTypeGo(&gfs)
 				callbackName := cabiCallbackName(c, m)
 				ret.WriteString(`func (this *` + goClassName + `) On` + m.SafeMethodName() + `(slot ` + goCbType + `) {
-					if ! this.isSubclass {
+					ok := C.` + goClassName + `_override_virtual_` + m.SafeMethodName() + `(unsafe.Pointer(this.h), C.intptr_t(cgo.NewHandle(slot)) )
+					if !ok {
 						panic("miqt: can only override virtual methods for directly constructed types")
 					}
-					C.` + goClassName + `_override_virtual_` + m.SafeMethodName() + `(unsafe.Pointer(this.h), C.intptr_t(cgo.NewHandle(slot)) )
 				}
 
 				//export ` + callbackName + `
@@ -1074,7 +1071,7 @@ import "C"
 			ret.WriteString(`
 			// Delete this object from C++ memory.
 			func (this *` + goClassName + `) Delete() {
-				C.` + goClassName + `_Delete(this.h, C.bool(this.isSubclass))
+				C.` + goClassName + `_Delete(this.h)
 			}
 				
 			// GoGC adds a Go Finalizer to this pointer, so that it will be deleted