ask kitten: Get readline to work even when stdout is redirected

kittens/ask/main.py

@@ -495,16 +495,20 @@ def main(args: List[str]) -> Response:
         loop.loop(phandler)
         return {'items': items, 'response': phandler.response}
 
-    import readline as rl
-    readline = rl
-    init_readline()
-    response = None
+    orig_stdout = os.dup(sys.stdout.fileno())
+    try:
+        with open(os.ctermid(), 'r') as tty:
+            os.dup2(tty.fileno(), sys.stdin.fileno())
+        with open(os.ctermid(), 'w') as tty:
+            os.dup2(tty.fileno(), sys.stdout.fileno())
+        import readline as rl
+        readline = rl
+        init_readline()
+        response = None
 
-    with alternate_screen(), HistoryCompleter(cli_opts.name):
-        if cli_opts.message:
-            print(styled(cli_opts.message, bold=True))
-
-        with suppress(KeyboardInterrupt, EOFError):
+        with alternate_screen(), HistoryCompleter(cli_opts.name), suppress(KeyboardInterrupt, EOFError):
+            if cli_opts.message:
+                print(styled(cli_opts.message, bold=True))
             if cli_opts.default:
                 def prefill_text() -> None:
                     readline.insert_text(cli_opts.default or '')
@@ -514,6 +518,10 @@ def prefill_text() -> None:
                 readline.set_pre_input_hook()
             else:
                 response = input(prompt)
+        sys.stdout.flush()
+        os.dup2(orig_stdout, sys.stdout.fileno())
+    finally:
+        os.close(orig_stdout)
     return {'items': items, 'response': response}
 
 

kittens/tui/operations.py

@@ -1,11 +1,12 @@
 #!/usr/bin/env python3
 # License: GPL v3 Copyright: 2018, Kovid Goyal <kovid at kovidgoyal.net>
 
+import os
 import sys
 from contextlib import contextmanager
 from enum import Enum, auto
 from functools import wraps
-from typing import IO, Any, Callable, Dict, Generator, Optional, TypeVar, Union
+from typing import Any, Callable, Dict, Generator, Optional, TypeVar, Union
 
 from kitty.fast_data_types import Color
 from kitty.rgb import color_as_sharp, to_color
@@ -348,13 +349,13 @@ def cursor(write: Callable[[str], None]) -> Generator[None, None, None]:
 
 
 @contextmanager
-def alternate_screen(f: Optional[IO[str]] = None) -> Generator[None, None, None]:
-    f = f or sys.stdout
-    print(set_mode(Mode.ALTERNATE_SCREEN), end='', file=f)
-    try:
-        yield
-    finally:
-        print(reset_mode(Mode.ALTERNATE_SCREEN), end='', file=f)
+def alternate_screen() -> Generator[None, None, None]:
+    with open(os.ctermid(), 'w') as f:
+        print(set_mode(Mode.ALTERNATE_SCREEN), end='', file=f, flush=True)
+        try:
+            yield
+        finally:
+            print(reset_mode(Mode.ALTERNATE_SCREEN), end='', file=f, flush=True)
 
 
 @contextmanager