fix for active message pump (#2148)

* fix for active message pump

* Add log file

* changelog

CHANGELOG.md

@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Added auto_scroll attribute to TextLog https://github.com/Textualize/textual/pull/2127
 - Added scroll_end switch to TextLog.write https://github.com/Textualize/textual/pull/2127
 - Added Screen.ModalScreen which prevents App from handling bindings. https://github.com/Textualize/textual/pull/2139
+- Added TEXTUAL_LOG env var which should be a path that Textual will write verbose logs to (textual devtools is generally preferred) https://github.com/Textualize/textual/pull/2148
 
 
 ## [0.16.0] - 2023-03-22

src/textual/__init__.py

@@ -6,6 +6,7 @@ from typing import TYPE_CHECKING, Callable
 import rich.repr
 from rich.console import RenderableType
 
+from . import constants
 from ._context import active_app
 from ._log import LogGroup, LogVerbosity
 
@@ -61,6 +62,16 @@ class Logger:
             print_args = (*args, *[f"{key}={value!r}" for key, value in kwargs.items()])
             print(*print_args)
             return
+        if constants.LOG_FILE:
+            output = " ".join(str(arg) for arg in args)
+            if kwargs:
+                key_values = " ".join(
+                    f"{key}={value!r}" for key, value in kwargs.items()
+                )
+                output = f"{output} {key_values}" if output else key_values
+
+            with open(constants.LOG_FILE, "a") as log_file:
+                print(output, file=log_file)
         if app.devtools is None or not app.devtools.is_connected:
             return
 

src/textual/constants.py

@@ -34,3 +34,6 @@ BORDERS = list(BORDER_CHARS)
 DEBUG: Final[bool] = get_environ_bool("TEXTUAL_DEBUG")
 
 DRIVER: Final[str | None] = get_environ("TEXTUAL_DRIVER", None)
+
+LOG_FILE: Final[str | None] = get_environ("TEXTUAL_LOG", None)
+"""A last resort log file that appends all logs, when devtools isn't working."""

src/textual/message_pump.py

@@ -399,7 +399,6 @@ class MessagePump(metaclass=MessagePumpMeta):
     def _start_messages(self) -> None:
         """Start messages task."""
         if self.app._running:
-            active_message_pump.set(self)
             self._task = create_task(
                 self._process_messages(), name=f"message pump {self}"
             )
@@ -409,6 +408,7 @@ class MessagePump(metaclass=MessagePumpMeta):
 
     async def _process_messages(self) -> None:
         self._running = True
+        active_message_pump.set(self)
 
         await self._pre_process()