Added code to create new Objective-C types at runtime, which will be important both for handling custom messages and for handling events.

darwintest/newtypes.go

@@ -0,0 +1,58 @@
+// 27 february 2014
+package main
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+// #cgo CFLAGS: -Dqqq
+// #cgo LDFLAGS: -lobjc -framework Foundation
+// #include <stdlib.h>
+// #include <objc/message.h>
+// #include <objc/objc.h>
+// #include <objc/runtime.h>
+// extern void ourMethod(id, SEL);
+// /* cgo doesn't like Nil */
+// extern Class NilClass; /* in runtimetest.go because of cgo limitations */
+import "C"
+
+var NSObject = C.object_getClass(objc_getClass("NSObject"))
+
+func newClass(name string) C.Class {
+	cname := C.CString(name)
+	defer C.free(unsafe.Pointer(cname))
+
+	c := C.objc_allocateClassPair(NSObject, cname, 0)
+	if c == C.NilClass {
+		panic("unable to create Objective-C class " + name)
+	}
+	return c
+}
+
+//export ourMethod
+func ourMethod(self C.id, sel C.SEL) {
+	fmt.Println("hello, world")
+}
+
+func addOurMethod(class C.Class, sel C.SEL) {
+	ty := []C.char{'v', '@', ':', 0}		// according to the example for class_addMethod()
+
+	// clas methods get stored in the metaclass; the objc_allocateClassPair() docs say this will work
+	metaclass := C.object_getClass(C.id(unsafe.Pointer(class)))
+	ok := C.class_addMethod(metaclass,
+		sel,
+		// using &C.ourMethod causes faults for some reason
+		C.IMP(unsafe.Pointer(C.ourMethod)),
+		&ty[0])
+	if ok == C.BOOL(C.NO) {
+		panic("unable to add ourMethod")
+	}
+}
+
+func mk(name string, sel C.SEL) C.id {
+	class := newClass(name)
+	addOurMethod(class, sel)
+	C.objc_registerClassPair(class)
+	return objc_getClass(name)
+}

darwintest/runtimetest.go

@@ -21,6 +21,7 @@ import (
 // id objc_msgSend_strarg(id obj, SEL sel, char *a) { return objc_msgSend(obj, sel, a); }
 // id objc_msgSend_NSRect_uint_uint_bool(id obj, SEL sel, CGRect a, NSUInteger b, NSUInteger c, BOOL d) { return objc_msgSend(obj, sel, a, b, c, d); }
 // id objc_msgSend_id(id obj, SEL sel, id a) { return objc_msgSend(obj, sel, a); }
+// Class NilClass = Nil; /* for newtypes.go */
 import "C"
 
 func objc_getClass(class string) C.id {
@@ -37,6 +38,12 @@ func sel_getUid(sel string) C.SEL {
 	return C.sel_getUid(csel)
 }
 
+func main() {
+	sel := sel_getUid("ourMethod")
+	C.objc_msgSend_noargs(mk("hello", sel),
+		sel)
+}
+
 const (
 	NSBorderlessWindowMask = 0
 	NSTitledWindowMask = 1 << 0
@@ -54,7 +61,7 @@ const (
 
 var alloc = sel_getUid("alloc")
 
-func main() {
+func wintest() {
 	NSWindow := objc_getClass("NSWindow")
 	NSWindowinit :=
 		sel_getUid("initWithContentRect:styleMask:backing:defer:")