Move implementation of +hold to Go

No need to pay python interpreter startup cost for --hold

kitty/entry_points.py

@@ -26,19 +26,9 @@ def runpy(args: List[str]) -> None:
 
 
 def hold(args: List[str]) -> None:
-    import subprocess
-    ret = 1
-    try:
-        ret = subprocess.Popen(args[1:]).wait()
-    except KeyboardInterrupt:
-        pass
-    except FileNotFoundError:
-        print(f'Could not find {args[1]!r} to execute', file=sys.stderr)
-    except Exception as e:
-        print(e, file=sys.stderr)
-    from kitty.utils import hold_till_enter
-    hold_till_enter()
-    raise SystemExit(ret)
+    from kitty.constants import kitty_tool_exe
+    args = ['kitty-tool', '__hold_till_enter__'] + args[1:]
+    os.execvp(kitty_tool_exe(), args)
 
 
 def open_urls(args: List[str]) -> None:

kitty/launch.py

@@ -15,7 +15,7 @@ from .child import Child
 from .cli import parse_args
 from .cli_stub import LaunchCLIOptions
 from .clipboard import set_clipboard_string, set_primary_selection
-from .constants import kitty_exe, shell_path
+from .constants import kitty_tool_exe, shell_path
 from .fast_data_types import (
     add_timer, get_boss, get_options, get_os_window_title, patch_color_profiles
 )
@@ -565,7 +565,7 @@ def launch(
     else:
         if opts.hold:
             cmd = kw['cmd'] or [shell_path]
-            kw['cmd'] = [kitty_exe(), '+hold'] + cmd
+            kw['cmd'] = [kitty_tool_exe(), '__hold_till_enter__'] + cmd
         if force_target_tab:
             tab = target_tab
         else:

kitty/session.py

@@ -8,7 +8,7 @@ from typing import (
 )
 
 from .cli_stub import CLIOptions
-from .constants import kitty_exe
+from .constants import kitty_tool_exe
 from .layout.interface import all_layouts
 from .options.types import Options
 from .options.utils import resize_window, to_layout_names, window_size
@@ -211,7 +211,7 @@ def create_sessions(
     if special_window is None:
         cmd = args.args if args and args.args else resolved_shell(opts)
         if args and args.hold:
-            cmd = [kitty_exe(), '+hold'] + cmd
+            cmd = [kitty_tool_exe(), '__hold_till_enter__'] + cmd
         from kitty.tabs import SpecialWindow
         cwd: Optional[str] = args.directory if respect_cwd and args else None
         special_window = SpecialWindow(cmd, cwd_from=cwd_from, cwd=cwd)

kitty/tabs.py

@@ -17,7 +17,7 @@ from typing import (
 from .borders import Border, Borders
 from .child import Child
 from .cli_stub import CLIOptions
-from .constants import appname, kitty_exe
+from .constants import appname, kitty_tool_exe
 from .fast_data_types import (
     GLFW_MOUSE_BUTTON_LEFT, GLFW_MOUSE_BUTTON_MIDDLE, GLFW_PRESS, GLFW_RELEASE, add_tab,
     attach_window, current_focused_os_window_id, detach_window, get_boss,
@@ -413,7 +413,7 @@ class Tab:  # {{{
                                     cmd[:0] = shlex.split(line)
                                 else:
                                     cmd[:0] = [resolved_shell(get_options())[0]]
-                                cmd[:0] = [kitty_exe(), '+hold']
+                                cmd[:0] = [kitty_tool_exe(), '__hold_till_enter__']
         fenv: Dict[str, str] = {}
         if env:
             fenv.update(env)

tools/cmd/tool/main.go

@@ -10,6 +10,7 @@ import (
 	"kitty/tools/cmd/clipboard"
 	"kitty/tools/cmd/edit_in_kitty"
 	"kitty/tools/cmd/update_self"
+	"kitty/tools/tui"
 )
 
 var _ = fmt.Print
@@ -25,4 +26,14 @@ func KittyToolEntryPoints(root *cli.Command) {
 	edit_in_kitty.EntryPoint(root)
 	// clipboard
 	clipboard.EntryPoint(root)
+	// __hold_till_enter__
+	root.AddSubCommand(&cli.Command{
+		Name:            "__hold_till_enter__",
+		Hidden:          true,
+		OnlyArgsAllowed: true,
+		Run: func(cmd *cli.Command, args []string) (rc int, err error) {
+			tui.ExecAndHoldTillEnter(args)
+			return
+		},
+	})
 }

tools/tui/hold.go

@@ -0,0 +1,72 @@
+// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>
+
+package tui
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"os/exec"
+
+	"kitty/tools/tui/loop"
+)
+
+var _ = fmt.Print
+
+func HoldTillEnter(start_with_newline bool) {
+	lp, err := loop.New(loop.NoAlternateScreen, loop.NoRestoreColors, loop.NoMouseTracking)
+	if err != nil {
+		return
+	}
+	lp.OnInitialize = func() (string, error) {
+		lp.SetCursorVisible(false)
+		if start_with_newline {
+			lp.QueueWriteString("\r\n")
+		}
+		lp.QueueWriteString("\x1b[1;32mPress Enter or Esc to exit\x1b[m")
+		return "", nil
+	}
+	lp.OnFinalize = func() string {
+		lp.SetCursorVisible(true)
+		return ""
+	}
+
+	lp.OnKeyEvent = func(event *loop.KeyEvent) error {
+		if event.MatchesPressOrRepeat("enter") || event.MatchesPressOrRepeat("esc") || event.MatchesPressOrRepeat("ctrl+c") || event.MatchesPressOrRepeat("ctrl+d") {
+			event.Handled = true
+			lp.Quit(0)
+		}
+		return nil
+	}
+	lp.Run()
+}
+
+func ExecAndHoldTillEnter(cmdline []string) {
+	if len(cmdline) == 0 {
+		HoldTillEnter(false)
+		os.Exit(0)
+	}
+	var cmd *exec.Cmd
+	if len(cmdline) == 1 {
+		cmd = exec.Command(cmdline[0])
+	} else {
+		cmd = exec.Command(cmdline[0], cmdline[1:]...)
+	}
+	cmd.Stdin = os.Stdin
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	var ee *exec.ExitError
+	err := cmd.Run()
+	is_exit_error := err != nil && errors.As(err, &ee)
+	if err != nil && !is_exit_error {
+		fmt.Fprintln(os.Stderr, err)
+	}
+	HoldTillEnter(true)
+	if err == nil {
+		os.Exit(0)
+	}
+	if is_exit_error {
+		os.Exit(ee.ExitCode())
+	}
+	os.Exit(1)
+}

tools/tui/loop/api.go

@@ -242,6 +242,14 @@ func (self *Loop) SetCursorShape(shape CursorShapes, blink bool) {
 	self.QueueWriteString(CursorShape(shape, blink))
 }
 
+func (self *Loop) SetCursorVisible(visible bool) {
+	if visible {
+		self.QueueWriteString(DECTCEM.EscapeCodeToSet())
+	} else {
+		self.QueueWriteString(DECTCEM.EscapeCodeToReset())
+	}
+}
+
 func (self *Loop) MoveCursorHorizontally(amt int) {
 	if amt != 0 {
 		suffix := "C"