simplify API of utils.Once

tools/utils/hostname.go

@@ -11,10 +11,10 @@ var _ = fmt.Print
 
 var hostname string = "*"
 
-var Hostname = (&Once[string]{Run: func() string {
+var Hostname = Once(func() string {
 	h, err := os.Hostname()
 	if err == nil {
 		return h
 	}
 	return ""
-}}).Get
+})

tools/utils/images/loading.go

@@ -264,9 +264,9 @@ func OpenNativeImageFromReader(f io.ReadSeeker) (ans *ImageData, err error) {
 	return
 }
 
-var MagickExe = (&utils.Once[string]{Run: func() string {
+var MagickExe = utils.Once(func() string {
 	return utils.FindExe("magick")
-}}).Get
+})
 
 func RunMagick(path string, cmd []string) ([]byte, error) {
 	if MagickExe() != "magick" {

tools/utils/mimetypes.go

@@ -44,7 +44,7 @@ func load_mime_file(filename string, mime_map map[string]string) error {
 	return nil
 }
 
-var UserMimeMap = (&Once[map[string]string]{Run: func() map[string]string {
+var UserMimeMap = Once(func() map[string]string {
 	conf_path := filepath.Join(ConfigDir(), "mime.types")
 	ans := make(map[string]string, 32)
 	err := load_mime_file(conf_path, ans)
@@ -52,7 +52,7 @@ var UserMimeMap = (&Once[map[string]string]{Run: func() map[string]string {
 		fmt.Fprintln(os.Stderr, "Failed to parse", conf_path, "for MIME types with error:", err)
 	}
 	return ans
-}}).Get
+})
 
 func is_rcfile(path string) bool {
 	name := filepath.Base(path)

tools/utils/once.go

@@ -10,7 +10,7 @@ import (
 
 var _ = fmt.Print
 
-type Once[T any] struct {
+type once[T any] struct {
 	done       uint32
 	mutex      sync.Mutex
 	cached_val T
@@ -18,14 +18,14 @@ type Once[T any] struct {
 	Run func() T
 }
 
-func (self *Once[T]) Get() T {
+func (self *once[T]) Get() T {
 	if atomic.LoadUint32(&self.done) == 0 {
 		self.do_slow()
 	}
 	return self.cached_val
 }
 
-func (self *Once[T]) do_slow() {
+func (self *once[T]) do_slow() {
 	self.mutex.Lock()
 	defer self.mutex.Unlock()
 	if atomic.LoadUint32(&self.done) == 0 {
@@ -33,3 +33,7 @@ func (self *Once[T]) do_slow() {
 		self.cached_val = self.Run()
 	}
 }
+
+func Once[T any](f func() T) func() T {
+	return (&once[T]{Run: f}).Get
+}

tools/utils/once_test.go

@@ -11,10 +11,10 @@ var _ = fmt.Print
 
 func TestOnce(t *testing.T) {
 	num := 0
-	var G = (&Once[string]{Run: func() string {
+	var G = Once(func() string {
 		num++
 		return fmt.Sprintf("%d", num)
-	}}).Get
+	})
 	G()
 	G()
 	G()

tools/utils/paths.go

@@ -62,7 +62,7 @@ func Abspath(path string) string {
 	return path
 }
 
-var KittyExe = (&Once[string]{Run: func() string {
+var KittyExe = Once(func() string {
 	exe, err := os.Executable()
 	if err == nil {
 		ans := filepath.Join(filepath.Dir(exe), "kitty")
@@ -71,7 +71,7 @@ var KittyExe = (&Once[string]{Run: func() string {
 		}
 	}
 	return os.Getenv("KITTY_PATH_TO_KITTY_EXE")
-}}).Get
+})
 
 func ConfigDirForName(name string) (config_dir string) {
 	if kcd := os.Getenv("KITTY_CONFIG_DIRECTORY"); kcd != "" {
@@ -117,11 +117,11 @@ func ConfigDirForName(name string) (config_dir string) {
 	return
 }
 
-var ConfigDir = (&Once[string]{Run: func() (config_dir string) {
+var ConfigDir = Once(func() (config_dir string) {
 	return ConfigDirForName("kitty.conf")
-}}).Get
+})
 
-var CacheDir = (&Once[string]{Run: func() (cache_dir string) {
+var CacheDir = Once(func() (cache_dir string) {
 	candidate := ""
 	if edir := os.Getenv("KITTY_CACHE_DIRECTORY"); edir != "" {
 		candidate = Abspath(Expanduser(edir))
@@ -136,7 +136,7 @@ var CacheDir = (&Once[string]{Run: func() (cache_dir string) {
 	}
 	os.MkdirAll(candidate, 0o755)
 	return candidate
-}}).Get
+})
 
 func macos_user_cache_dir() string {
 	// Sadly Go does not provide confstr() so we use this hack.
@@ -176,7 +176,7 @@ func macos_user_cache_dir() string {
 	return ""
 }
 
-var RuntimeDir = (&Once[string]{Run: func() (runtime_dir string) {
+var RuntimeDir = Once(func() (runtime_dir string) {
 	var candidate string
 	if q := os.Getenv("KITTY_RUNTIME_DIRECTORY"); q != "" {
 		candidate = q
@@ -199,7 +199,7 @@ var RuntimeDir = (&Once[string]{Run: func() (runtime_dir string) {
 		os.Chmod(candidate, 0o700)
 	}
 	return candidate
-}}).Get
+})
 
 type Walk_callback func(path, abspath string, d fs.DirEntry, err error) error
 

tools/utils/which.go

@@ -13,7 +13,7 @@ import (
 
 var _ = fmt.Print
 
-var DefaultExeSearchPaths = (&Once[[]string]{Run: func() []string {
+var DefaultExeSearchPaths = Once(func() []string {
 	candidates := [...]string{"/usr/local/bin", "/opt/bin", "/opt/homebrew/bin", "/usr/bin", "/bin", "/usr/sbin", "/sbin"}
 	ans := make([]string, 0, len(candidates))
 	for _, x := range candidates {
@@ -22,7 +22,7 @@ var DefaultExeSearchPaths = (&Once[[]string]{Run: func() []string {
 		}
 	}
 	return ans
-}}).Get
+})
 
 func Which(cmd string, paths ...string) string {
 	if strings.Contains(cmd, string(os.PathSeparator)) {