Switch the Native method to return a uintptr.

This change modifies the function signature of the various Native
methods from returing a C pointer to returning a uintptr.  This change
is being made for the following reasons:

1) cgo's psuedo package qualifier is replaced with the package local
   prefix `_Ctype_'.  Because these prefixes are package local, it
   is impossible to use the returned pointer directly in data
   structures without first type switching the result with the unsafe
   package.  When the caller is not interested in using the pointer
   for other cgo calls (for example, creating a map of GObjects to
   Go structs to look up additional context from callbacks),
   returning a uintptr does not require any additional type switches,
   and more importantly does not require the use of the unsafe package.

2) When the returned pointer is meant to be used as an argument to a
   cgo function, the returned result must fisrt be type switched to a
   package-local C type using the unsafe package.  While returning a
   uintptr does not make this process any easier, it also doesn't make
   it any more inconvenient.

Author: jrick

cairo/cairo.go

@@ -166,7 +166,7 @@ func (v *Object) Connect(detailedSignal string, f interface{}, userData ...inter
 
 	C._g_closure_add_finalize_notifier(closure)
 
-	c := C.g_signal_connect_closure(C.gpointer(v.Native()),
+	c := C.g_signal_connect_closure(C.gpointer(v.native()),
 		(*C.gchar)(cstr), closure, gbool(false))
 	handle := SignalHandle(c)
 
@@ -287,7 +287,7 @@ func goMarshal(closure *C.GClosure, retValue *C.GValue,
 			fmt.Fprintf(os.Stderr,
 				"cannot save callback return value: %v", err)
 		} else {
-			*retValue = *g.Native()
+			*retValue = *g.native()
 		}
 	}
 }
@@ -436,7 +436,7 @@ func (v *Object) toGObject() *C.GObject {
 	if v == nil {
 		return nil
 	}
-	return v.Native()
+	return v.native()
 }
 
 func (v *Object) toObject() *Object {
@@ -448,23 +448,28 @@ func newObject(p *C.GObject) *Object {
 	return &Object{GObject: p}
 }
 
-// Native returns a pointer to the underlying GObject.
-func (v *Object) Native() *C.GObject {
+// native returns a pointer to the underlying GObject.
+func (v *Object) native() *C.GObject {
 	if v == nil || v.GObject == nil {
 		return nil
 	}
 	p := unsafe.Pointer(v.GObject)
 	return C.toGObject(p)
 }
 
+// Native returns a pointer to the underlying GObject.
+func (v *Object) Native() uintptr {
+	return uintptr(unsafe.Pointer(v.native()))
+}
+
 // IsA is a wrapper around g_type_is_a().
 func (v *Object) IsA(typ Type) bool {
 	return gobool(C.g_type_is_a(C.GType(v.TypeFromInstance()), C.GType(typ)))
 }
 
 // TypeFromInstance is a wrapper around g_type_from_instance().
 func (v *Object) TypeFromInstance() Type {
-	c := C._g_type_from_instance(C.gpointer(unsafe.Pointer(v.Native())))
+	c := C._g_type_from_instance(C.gpointer(unsafe.Pointer(v.native())))
 	return Type(c)
 }
 
@@ -641,13 +646,13 @@ func (v *Object) Emit(s string, args ...interface{}) (interface{}, error) {
 	if err != nil {
 		return nil, errors.New("Error converting Object to GValue: " + err.Error())
 	}
-	C.val_list_insert(valv, C.int(0), val.Native())
+	C.val_list_insert(valv, C.int(0), val.native())
 	for i := range args {
 		val, err := GValue(args[i])
 		if err != nil {
 			return nil, fmt.Errorf("Error converting arg %d to GValue: %s", i, err.Error())
 		}
-		C.val_list_insert(valv, C.int(i+1), val.Native())
+		C.val_list_insert(valv, C.int(i+1), val.native())
 	}
 
 	t := v.TypeFromInstance()
@@ -658,7 +663,7 @@ func (v *Object) Emit(s string, args ...interface{}) (interface{}, error) {
 	if err != nil {
 		return nil, errors.New("Error creating Value for return value")
 	}
-	C.g_signal_emitv(valv, id, C.GQuark(0), ret.Native())
+	C.g_signal_emitv(valv, id, C.GQuark(0), ret.native())
 
 	return ret.GoValue()
 }
@@ -687,9 +692,22 @@ func (v *Object) HandlerDisconnect(handle SignalHandle) {
 
 // InitiallyUnowned is a representation of GLib's GInitiallyUnowned.
 type InitiallyUnowned struct {
+	// This must be a pointer so copies of the ref-sinked object
+	// do not outlive the original object, causing an unref
+	// finalizer to prematurely run.
 	*Object
 }
 
+// Native returns a pointer to the underlying GObject.  This is implemented
+// here rather than calling Native on the embedded Object to prevent a nil
+// pointer dereference.
+func (v *InitiallyUnowned) Native() uintptr {
+	if v == nil || v.Object == nil {
+		return uintptr(unsafe.Pointer(nil))
+	}
+	return v.Object.Native()
+}
+
 /*
  * GSList
  */
@@ -714,11 +732,16 @@ type Value struct {
 	GValue C.GValue
 }
 
-// Native returns a pointer to the underlying GValue.
-func (v *Value) Native() *C.GValue {
+// native returns a pointer to the underlying GValue.
+func (v *Value) native() *C.GValue {
 	return &v.GValue
 }
 
+// Native returns a pointer to the underlying GValue.
+func (v *Value) Native() uintptr {
+	return uintptr(unsafe.Pointer(v.native()))
+}
+
 // ValueAlloc allocates a Value and sets a runtime finalizer to call
 // g_value_unset() on the underlying GValue after leaving scope.
 // ValueAlloc() returns a non-nil error if the allocation failed.
@@ -747,17 +770,17 @@ func ValueInit(t Type) (*Value, error) {
 }
 
 func (v *Value) unset() {
-	C.g_value_unset(v.Native())
+	C.g_value_unset(v.native())
 }
 
 // Type is a wrapper around the G_VALUE_HOLDS_GTYPE() macro and
 // the g_value_get_gtype() function.  GetType() returns TYPE_INVALID if v
 // does not hold a Type, or otherwise returns the Type of v.
 func (v *Value) Type() (actual Type, fundamental Type, err error) {
-	if !gobool(C._g_is_value(v.Native())) {
+	if !gobool(C._g_is_value(v.native())) {
 		return actual, fundamental, errors.New("invalid GValue")
 	}
-	cActual := C._g_value_type(v.Native())
+	cActual := C._g_value_type(v.native())
 	cFundamental := C._g_value_fundamental(cActual)
 	return Type(cActual), Type(cFundamental), nil
 }
@@ -1091,7 +1114,7 @@ func (v *Value) GoValue() (interface{}, error) {
 		return nil, err
 	}
 
-	rv, err := f(uintptr(unsafe.Pointer(v.Native())))
+	rv, err := f(uintptr(unsafe.Pointer(v.native())))
 	if obj, ok := rv.(IObject); ok {
 		o := obj.toObject()
 		o.RefSink()
@@ -1102,72 +1125,72 @@ func (v *Value) GoValue() (interface{}, error) {
 
 // SetBool is a wrapper around g_value_set_boolean().
 func (v *Value) SetBool(val bool) {
-	C.g_value_set_boolean(v.Native(), gbool(val))
+	C.g_value_set_boolean(v.native(), gbool(val))
 }
 
 // SetSChar is a wrapper around g_value_set_schar().
 func (v *Value) SetSChar(val int8) {
-	C.g_value_set_schar(v.Native(), C.gint8(val))
+	C.g_value_set_schar(v.native(), C.gint8(val))
 }
 
 // SetInt64 is a wrapper around g_value_set_int64().
 func (v *Value) SetInt64(val int64) {
-	C.g_value_set_int64(v.Native(), C.gint64(val))
+	C.g_value_set_int64(v.native(), C.gint64(val))
 }
 
 // SetInt is a wrapper around g_value_set_int().
 func (v *Value) SetInt(val int) {
-	C.g_value_set_int(v.Native(), C.gint(val))
+	C.g_value_set_int(v.native(), C.gint(val))
 }
 
 // SetUChar is a wrapper around g_value_set_uchar().
 func (v *Value) SetUChar(val uint8) {
-	C.g_value_set_uchar(v.Native(), C.guchar(val))
+	C.g_value_set_uchar(v.native(), C.guchar(val))
 }
 
 // SetUInt64 is a wrapper around g_value_set_uint64().
 func (v *Value) SetUInt64(val uint64) {
-	C.g_value_set_uint64(v.Native(), C.guint64(val))
+	C.g_value_set_uint64(v.native(), C.guint64(val))
 }
 
 // SetUInt is a wrapper around g_value_set_uint().
 func (v *Value) SetUInt(val uint) {
-	C.g_value_set_uint(v.Native(), C.guint(val))
+	C.g_value_set_uint(v.native(), C.guint(val))
 }
 
 // SetFloat is a wrapper around g_value_set_float().
 func (v *Value) SetFloat(val float32) {
-	C.g_value_set_float(v.Native(), C.gfloat(val))
+	C.g_value_set_float(v.native(), C.gfloat(val))
 }
 
 // SetDouble is a wrapper around g_value_set_double().
 func (v *Value) SetDouble(val float64) {
-	C.g_value_set_double(v.Native(), C.gdouble(val))
+	C.g_value_set_double(v.native(), C.gdouble(val))
 }
 
 // SetString is a wrapper around g_value_set_string().
 func (v *Value) SetString(val string) {
 	cstr := C.CString(val)
 	defer C.free(unsafe.Pointer(cstr))
-	C.g_value_set_string(v.Native(), (*C.gchar)(cstr))
+	C.g_value_set_string(v.native(), (*C.gchar)(cstr))
 }
 
 // SetInstance is a wrapper around g_value_set_instance().
 func (v *Value) SetInstance(instance uintptr) {
-	C.g_value_set_instance(v.Native(), C.gpointer(instance))
+	C.g_value_set_instance(v.native(), C.gpointer(instance))
 }
 
 // SetPointer is a wrapper around g_value_set_pointer().
 func (v *Value) SetPointer(p uintptr) {
-	C.g_value_set_pointer(v.Native(), C.gpointer(p))
+	C.g_value_set_pointer(v.native(), C.gpointer(p))
 }
 
 // GetString is a wrapper around g_value_get_string().  GetString()
 // returns a non-nil error if g_value_get_string() returned a NULL
 // pointer to distinguish between returning a NULL pointer and returning
 // an empty string.
 func (v *Value) GetString() (string, error) {
-	c := C.g_value_get_string(v.Native())
+	c := C.g_value_get_string(v.native())
 	if c == nil {
 		return "", errNilPtr
 	}

gdk/gdk.go

@@ -62,7 +62,6 @@ func main() {
 	}
 
 	setupPropertyCheckboxes(tv, box, props)
-	box.PackStart(tv, true, true, 0)
 
 	win.ShowAll()