autoreleasepool support (#50)

Implements `Autorelease(func())` to run the body with an active autoreleasepool.

Existing calls to `NSAutoreleasePool` have been replaced and wrapped with this block helper.

Fixes #12

objc/autoreleasepool.go

@@ -0,0 +1,19 @@
+package objc
+
+/*
+#cgo LDFLAGS: -lobjc -framework Foundation
+extern void objc_autoreleasePoolPop(void* pool);
+extern void* objc_autoreleasePoolPush(void);
+*/
+import "C"
+import "runtime"
+
+func Autorelease(body func()) {
+	// ObjC autoreleasepools are thread-local, so we need the body to be locked to
+	// the same OS thread.
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+	pool := C.objc_autoreleasePoolPush()
+	defer C.objc_autoreleasePoolPop(pool)
+	body()
+}

objc/autoreleasepool_test.go

@@ -0,0 +1,27 @@
+package objc
+
+import (
+	"testing"
+)
+
+type AutoreleaseDealloc struct {
+	Object `objc:"AutoreleaseDealloc : NSObject"`
+}
+
+func TestAutorelease(t *testing.T) {
+	c := NewClassFromStruct(AutoreleaseDealloc{})
+	deallocCount := 0
+	c.AddMethod("dealloc", func(o Object) {
+		deallocCount++
+		o.SendSuper("dealloc")
+	})
+	RegisterClass(c)
+
+	Autorelease(func() {
+		dc := GetClass("AutoreleaseDealloc").Alloc().Init()
+		dc.Autorelease()
+	})
+	if deallocCount != 1 {
+		t.Errorf("expected dealloc to be called once, but got: %d", deallocCount)
+	}
+}

objc/iboutlet_test.go

@@ -46,37 +46,35 @@ func NSStringFromString(str string) Object {
 func TestIBOutletKeyValueCodingImpl(t *testing.T) {
 	registerIBOutletTestClass()
 
-	pool := GetClass("NSAutoreleasePool").Send("alloc").Send("init")
-	defer pool.Send("release")
+	Autorelease(func() {
+		ibo := GetClass("IBOutletTester").Send("alloc").Send("init")
+		ibo.Send("setValue:forKey:", ibo, NSStringFromString("Myself").Autorelease())
 
-	ibo := GetClass("IBOutletTester").Send("alloc").Send("init")
-	ibo.Send("setValue:forKey:", ibo, NSStringFromString("Myself").Autorelease())
-
-	if ibo.Send("myselfIsNil").Bool() {
-		t.Fatal("nil iboutlet, value not properly set for key")
-	}
+		if ibo.Send("myselfIsNil").Bool() {
+			t.Fatal("nil iboutlet, value not properly set for key")
+		}
 
-	if !ibo.Send("myselfIsMyself").Bool() {
-		t.Fatal("value not set, or incorrectly set.")
-	}
+		if !ibo.Send("myselfIsMyself").Bool() {
+			t.Fatal("value not set, or incorrectly set.")
+		}
+	})
 }
 
 func TestIBOutletSetter(t *testing.T) {
 	registerIBOutletTestClass()
 
-	pool := GetClass("NSAutoreleasePool").Send("alloc").Send("init")
-	defer pool.Send("release")
+	Autorelease(func() {
+		ibo := GetClass("IBOutletTester").Send("alloc").Send("init")
+		ibo.Send("setMyself:", ibo)
 
-	ibo := GetClass("IBOutletTester").Send("alloc").Send("init")
-	ibo.Send("setMyself:", ibo)
-
-	if ibo.Send("myselfIsNil").Bool() {
-		t.Fatal("nil iboutlet, value not properly set for key")
-	}
+		if ibo.Send("myselfIsNil").Bool() {
+			t.Fatal("nil iboutlet, value not properly set for key")
+		}
 
-	if !ibo.Send("myselfIsMyself").Bool() {
-		t.Fatal("value not set, or incorrectly set.")
-	}
+		if !ibo.Send("myselfIsMyself").Bool() {
+			t.Fatal("value not set, or incorrectly set.")
+		}
+	})
 }
 
 type Shadow struct {

objc/msg_test.go

@@ -14,10 +14,13 @@ import (
 )
 
 func TestMain(m *testing.M) {
-	pool := GetClass("NSAutoreleasePool").Alloc().Init()
-	defer pool.Release()
-
-	os.Exit(m.Run())
+	// default to 1 to still exit with an error if a bug leads to not updating the
+	// status
+	status := 1
+	Autorelease(func() {
+		status = m.Run()
+	})
+	os.Exit(status)
 }
 
 func BenchmarkSendMsg(b *testing.B) {

objc/object.go

@@ -177,14 +177,14 @@ func (obj object) CString() string {
 
 func (obj object) String() string {
 	// TODO: some kind of recover to catch when this doesnt work
-
-	pool := GetClass("NSAutoreleasePool").Alloc().Init()
-	defer pool.Release()
-
-	bytes := obj.Send("description").Send("UTF8String")
-	if bytes.Pointer() == 0 {
-		return "(nil)"
-	}
-
-	return bytes.CString()
+	var r string
+	Autorelease(func() {
+		bytes := obj.Send("description").Send("UTF8String")
+		if bytes.Pointer() == 0 {
+			r = "(nil)"
+		} else {
+			r = bytes.CString()
+		}
+	})
+	return r
 }