objc: remove unsafe usage from test (#57)

Add support for NewIMP to take a pointer to an Objective-C struct. This allows the removal of all uses of package unsafe from the tests by creating a struct that matches the structure of the Objective-C object.

commit: fbeb60f11c9695c15c8d6a15a5b22bc185161b80
author: TotallyGamerJet · 3y ago · 2022-10-31 03:44 UTC
committer: GitHub · 3y ago · 2022-10-31 03:44 UTC
parent: 63d5487
signature: GPG Unverified4AEE18F83AFDEB23 The key is unknown

2 files · +20 -12

M objc/objc_runtime_darwin.go +9 -3


@@ -168,8 +168,10 @@ func GetProtocol(name string) *Protocol {
168	168		// IMP is a function pointer that can be called by Objective-C code.
169	169		type IMP uintptr
170	170
171		-	// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments. It returns an IMP function
172		-	// pointer that can be called by Objective-C code. The function pointer is never deallocated.
	171	+	// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments.
	172	+	// ID may instead be a pointer to a struct whose first field has type Class.
	173	+	// It returns an IMP function pointer that can be called by Objective-C code.
	174	+	// The function pointer is never deallocated.
173	175		func NewIMP(fn interface{}) IMP {
174	176		ty := reflect.TypeOf(fn)
175	177		if ty.Kind() != reflect.Func {

@@ -180,7 +182,11 @@ func NewIMP(fn interface{}) IMP {
180	182		switch {
181	183		case ty.NumIn() < 2:
182	184		fallthrough
183		-	case ty.In(0).Kind() != reflect.Uintptr:
	185	+	case ty.In(0).Kind() != reflect.Uintptr && // checks if it's objc.ID
	186	+	// or that it's a pointer to a struct
	187	+	(ty.In(0).Kind() != reflect.Pointer \|\| ty.In(0).Elem().Kind() != reflect.Struct \|\|
	188	+	// and that the structs first field is an objc.Class
	189	+	ty.In(0).Elem().Field(0).Type != reflect.TypeOf(Class(0))):
184	190		fallthrough
185	191		case ty.In(1).Kind() != reflect.Uintptr:
186	192		panic("objc: NewIMP must take a (id, SEL) as its first two arguments")

 // IMP is a function pointer that can be called by Objective-C code.
 type IMP uintptr
-// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments. It returns an IMP function
+// NewIMP takes a Go function that takes (ID, SEL) as its first two arguments.
-// pointer that can be called by Objective-C code. The function pointer is never deallocated.
+// ID may instead be a pointer to a struct whose first field has type Class.
+// It returns an IMP function pointer that can be called by Objective-C code.
+// The function pointer is never deallocated.
 func NewIMP(fn interface{}) IMP {
 	ty := reflect.TypeOf(fn)
 	if ty.Kind() != reflect.Func {
 	switch {
 	case ty.NumIn() < 2:
 		fallthrough
-	case ty.In(0).Kind() != reflect.Uintptr:
+	case ty.In(0).Kind() != reflect.Uintptr && // checks if it's objc.ID
+		// or that it's a pointer to a struct
+		(ty.In(0).Kind() != reflect.Pointer || ty.In(0).Elem().Kind() != reflect.Struct ||
+			// and that the structs first field is an objc.Class
+			ty.In(0).Elem().Field(0).Type != reflect.TypeOf(Class(0))):
 		fallthrough
 	case ty.In(1).Kind() != reflect.Uintptr:
 		panic("objc: NewIMP must take a (id, SEL) as its first two arguments")

M objc/objc_runtime_darwin_test.go +11 -9


@@ -5,7 +5,6 @@ package objc_test
5	5
6	6		import (
7	7		"fmt"
8		-	"unsafe"
9	8
10	9		"github.com/ebitengine/purego"
11	10		"github.com/ebitengine/purego/objc"

@@ -24,20 +23,23 @@ func ExampleAllocateClassPair() {
24	23		}
25	24
26	25		func ExampleClass_AddIvar() {
	26	+	type barObject struct {
	27	+	isa objc.Class
	28	+	bar int
	29	+	}
27	30		var class = objc.AllocateClassPair(objc.GetClass("NSObject"), "BarObject", 0)
28	31		class.AddIvar("bar", int(0), "q")
29		-	var barOffset = class.InstanceVariable("bar").Offset()
30		-	class.AddMethod(objc.RegisterName("bar"), objc.NewIMP(func(self objc.ID, _cmd objc.SEL) int {
31		-	return (int)(unsafe.Pointer(uintptr(unsafe.Pointer(self)) + barOffset))
	32	+	class.AddMethod(objc.RegisterName("bar"), objc.NewIMP(func(self *barObject, _cmd objc.SEL) int {
	33	+	return self.bar
32	34		}), "q@:")
33		-	class.AddMethod(objc.RegisterName("setBar:"), objc.NewIMP(func(self objc.ID, _cmd objc.SEL, bar int) {
34		-	(int)(unsafe.Pointer(uintptr(unsafe.Pointer(self)) + barOffset)) = bar
	35	+	class.AddMethod(objc.RegisterName("setBar:"), objc.NewIMP(func(self *barObject, _cmd objc.SEL, bar int) {
	36	+	self.bar = bar
35	37		}), "v@:q")
36	38		class.Register()
37	39
38		-	var barObject = objc.ID(class).Send(objc.RegisterName("new"))
39		-	barObject.Send(objc.RegisterName("setBar:"), 123)
40		-	var bar = int(barObject.Send(objc.RegisterName("bar")))
	40	+	var object = objc.ID(class).Send(objc.RegisterName("new"))
	41	+	object.Send(objc.RegisterName("setBar:"), 123)
	42	+	var bar = int(object.Send(objc.RegisterName("bar")))
41	43		fmt.Println(bar)
42	44		// Output: 123
43	45		}

 import (
 	"fmt"
-	"unsafe"
 	"github.com/ebitengine/purego"
 	"github.com/ebitengine/purego/objc"
 }
 func ExampleClass_AddIvar() {
+	type barObject struct {
+		isa objc.Class
+		bar int
+	}
 	var class = objc.AllocateClassPair(objc.GetClass("NSObject"), "BarObject", 0)
 	class.AddIvar("bar", int(0), "q")
-	var barOffset = class.InstanceVariable("bar").Offset()
+	class.AddMethod(objc.RegisterName("bar"), objc.NewIMP(func(self *barObject, _cmd objc.SEL) int {
-	class.AddMethod(objc.RegisterName("bar"), objc.NewIMP(func(self objc.ID, _cmd objc.SEL) int {
+		return self.bar
-		return *(*int)(unsafe.Pointer(uintptr(unsafe.Pointer(self)) + barOffset))
 	}), "q@:")
-	class.AddMethod(objc.RegisterName("setBar:"), objc.NewIMP(func(self objc.ID, _cmd objc.SEL, bar int) {
+	class.AddMethod(objc.RegisterName("setBar:"), objc.NewIMP(func(self *barObject, _cmd objc.SEL, bar int) {
-		*(*int)(unsafe.Pointer(uintptr(unsafe.Pointer(self)) + barOffset)) = bar
+		self.bar = bar
 	}), "v@:q")
 	class.Register()
-	var barObject = objc.ID(class).Send(objc.RegisterName("new"))
+	var object = objc.ID(class).Send(objc.RegisterName("new"))
-	barObject.Send(objc.RegisterName("setBar:"), 123)
+	object.Send(objc.RegisterName("setBar:"), 123)
-	var bar = int(barObject.Send(objc.RegisterName("bar")))
+	var bar = int(object.Send(objc.RegisterName("bar")))
 	fmt.Println(bar)
 	// Output: 123
 }