Updated docs for app.run (#2414)

* fix run app from python

* updated run

* remove function

* update help

* doc update

CHANGELOG.md

@@ -5,6 +5,12 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [0.22.1] - 2023-04-28
+
+### Fixed
+
+- Fixed `textual run` issue https://github.com/Textualize/textual/issues/2391
+
 ## [0.22.0] - 2023-04-27
 
 ### Fixed

docs/guide/devtools.md

@@ -8,7 +8,7 @@
 
 Textual comes with a command line application of the same name. The `textual` command is a super useful tool that will help you to build apps.
 
-Take a moment to look through the available sub-commands. There will be even more helpful tools here in the future.
+Take a moment to look through the available subcommands. There will be even more helpful tools here in the future.
 
 ```bash
 textual --help
@@ -17,25 +17,48 @@ textual --help
 
 ## Run
 
-You can run Textual apps with the `run` subcommand. If you supply a path to a Python file it will load and run the application.
+The `run` sub-command runs Textual apps. If you supply a path to a Python file it will load and run the app.
 
 ```bash
 textual run my_app.py
 ```
 
-The `run` sub-command will first look for a `App` instance called `app` in the global scope of your Python file. If there is no `app`, it will create an instance of the first `App` class it finds and run that.
+This is equivalent to running `python my_app.py` from the command prompt, but will allow you to set various switches which can help you debug, such as `--dev` which enable the [Console](#console).
 
-Alternatively, you can add the name of an `App` instance or class after a colon to run a specific app in the Python file. Here's an example:
+See the `run` subcommand's help for details:
 
 ```bash
-textual run my_app.py:alternative_app
+textual run --help
+```
+
+You can also run Textual apps from a python import.
+The following command would import `music.play` and run a Textual app in that module:
+
+```bash
+textual run music.play
+```
+
+This assumes you have a Textual app instance called `app` in `music.play`.
+If your app has a different name, you can append it after a colon:
+
+```bash
+textual run music.play:MusicPlayerApp
 ```
 
 !!! note
 
-    If the Python file contains a call to app.run() then you can launch the file as you normally would any other Python program. Running your app via `textual run` will give you access to a few Textual features such as live editing of CSS files.
+    This works for both Textual app *instances* and *classes*.
 
 
+### Running from commands
+
+If your app is installed as a command line script, you can use the `-c` switch to run it.
+For instance, the following will run the `textual colors` command:
+
+```bash
+textual run -c textual colors
+```
+
 ## Live editing
 
 If you combine the `run` command with the `--dev` switch your app will run in *development mode*.

src/textual/cli/_run.py

@@ -17,7 +17,11 @@ from typing import NoReturn, Sequence
 EXEC_SCRIPT = Template(
     """\
 from textual.app import App
-from $MODULE import $APP as app;
+try:
+    from $MODULE import $APP as app;
+except ImportError:
+    raise SystemExit("Unable to import '$APP' from module '$MODULE'") from None
+
 if isinstance(app, App):
     # If we imported an app, run it
     app.run()
@@ -111,25 +115,6 @@ def exec_command(
     os.execvpe(command, [command, *args], environment)
 
 
-def check_import(module_name: str, app_name: str) -> bool:
-    """Check if a symbol can be imported.
-
-    Args:
-        module_name: Name of the module
-        app_name: Name of the app.
-
-    Returns:
-        True if the app may be imported from the module.
-    """
-
-    try:
-        sys.path.insert(0, "")
-        module = importlib.import_module(module_name)
-    except ImportError as error:
-        return False
-    return hasattr(module, app_name)
-
-
 def exec_import(
     import_name: str, args: Sequence[str], environment: dict[str, str]
 ) -> NoReturn:
@@ -147,9 +132,6 @@ def exec_import(
     module, _colon, app = import_name.partition(":")
     app = app or "app"
 
-    if not check_import(module, app):
-        raise ExecImportError(f"Unable to import {app!r} from  {import_name!r}")
-
     script = EXEC_SCRIPT.substitute(MODULE=module, APP=app)
     # Compiling the script will raise a SyntaxError if there are any invalid symbols
     compile(script, "textual-exec", "exec")

src/textual/cli/cli.py

@@ -147,16 +147,16 @@ def _run_app(
 ) -> None:
     """Run a Textual app.
 
-    The code to run may be given as a path (ending with .py) or as a Python
-    import, which will load the code and run an app called "app". You may optionally
-    add a colon plus the class or class instance you want to run.
+    The app to run may be given as a path (ending with .py) which will be equivalent to running the
+    script with python, or as a Python import which will import and run an app called "app".
+
+    In the case of an import, you can import and run an alternative app by appending a colon followed
+    by the name of the app instance or class.
 
     Here are some examples:
 
         textual run foo.py
 
-        textual run foo.py:MyApp
-
         textual run module.foo
 
         textual run module.foo:MyApp

src/textual/widgets/_tabs.py

@@ -404,7 +404,9 @@ class Tabs(Widget, can_focus=True):
             active_tab = self.query_one(f"#tabs-list > #{active}", Tab)
             self.query("#tabs-list > Tab.-active").remove_class("-active")
             active_tab.add_class("-active")
-            self._highlight_active(animate=previously_active != "")
+            self.call_after_refresh(
+                self._highlight_active, animate=previously_active != ""
+            )
             self.post_message(self.TabActivated(self, active_tab))
         else:
             underline = self.query_one(Underline)