func sourceAttach(src *C.struct__GSource, rf reflect.Value, args ...interface{}) (SourceHandle, error) {
	if src == nil {
		return 0, errNilPtr
	}

	// rf must be a func with no parameters.
	if rf.Type().Kind() != reflect.Func {
		C.g_source_destroy(src)
		return 0, errors.New("rf is not a function")
	}

	// Create a new GClosure from f that invalidates itself when
	// f returns false.  The error is ignored here, as this will
	// always be a function.
	var closure *C.GClosure
	closure, _ = ClosureNew(rf.Interface(), args...)

	// Remove closure context when closure is finalized.
	C._g_closure_add_finalize_notifier(closure)

	// Set closure to run as a callback when the idle source runs.
	C.g_source_set_closure(src, closure)

	// Attach the idle source func to the default main event loop
	// context.
	cid := C.g_source_attach(src, nil)
	return SourceHandle(cid), nil
}
func sourceAttach(src *C.struct__GSource, rf reflect.Value, args ...interface{}) (SourceHandle, error) {
	if src == nil {
		return 0, errNilPtr
	}

	// rf must be a func with no parameters.
	if rf.Type().Kind() != reflect.Func {
		C.g_source_destroy(src)
		return 0, errors.New("rf is not a function")
	}

	// Create a new GClosure from f that invalidates itself when
	// f returns false.  The error is ignored here, as this will
	// always be a function.
	var closure *C.GClosure
	closure, _ = ClosureNew(rf.Interface(), args...)

	// Remove closure context when closure is finalized.
	C._g_closure_add_finalize_notifier(closure)

	// Set closure to run as a callback when the idle source runs.
	C.g_source_set_closure(src, closure)

	// Attach the idle source func to the default main event loop
	// context.
	cid := C.g_source_attach(src, nil)
	return SourceHandle(cid), nil
}
// sourceAttach attaches a source to the default main loop context.