Tweak main app lifecycle to remove need for suspending updates.

android/src/toga_android/app.py

@@ -191,21 +191,21 @@ def native(self):
     # App lifecycle
     ######################################################################
 
-    def create(self):
-        # The `_listener` listens for activity event callbacks. For simplicity,
-        # the app's `.native` is the listener's native Java class.
-        self._listener = TogaApp(self)
-        # Call user code to populate the main window
-        self.interface._startup()
-        self.create_app_commands()
-
     def main_loop(self):
         # In order to support user asyncio code, start the Python/Android cooperative event loop.
         self.loop.run_forever_cooperatively()
 
-        # On Android, Toga UI integrates automatically into the main Android event loop by virtue
-        # of the Android Activity system.
-        self.create()
+        # On Android, Toga UI integrates automatically into the main Android event loop
+        # by virtue of the Android Activity system. The `_listener` listens for activity
+        # event callbacks. For simplicity, the app's `.native` is the listener's native
+        # Java class.
+        self._listener = TogaApp(self)
+        # Call user code to populate the main window
+        self.interface._startup()
+
+    def finalize(self):
+        self.create_app_commands()
+        self.create_menus()
 
     def set_main_window(self, window):
         if window is None:

android/src/toga_android/window.py

@@ -27,8 +27,6 @@ def onGlobalLayout(self):
 
 
 class Window(Container):
-    has_titlebar = False
-
     def __init__(self, interface, title, position, size):
         super().__init__()
         self.interface = interface
@@ -48,8 +46,11 @@ def set_app(self, app):
         )
         self.set_title(self._initial_title)
 
-        if not self.has_titlebar:
-            self.app.native.getSupportActionBar().hide()
+        self._configure_titlebar()
+
+    def _configure_titlebar(self):
+        # Simple windows hide the titlebar.
+        self.app.native.getSupportActionBar().hide()
 
     def get_title(self):
         return str(self.app.native.getTitle())
@@ -121,4 +122,6 @@ def get_image_data(self):
 
 
 class MainWindow(Window):
-    has_titlebar = True
+    def _configure_titlebar(self):
+        # The titlebar will be visible by default.
+        pass

cocoa/src/toga_cocoa/app.py

@@ -1,6 +1,5 @@
 import asyncio
 import inspect
-import os
 import sys
 from pathlib import Path
 from urllib.parse import unquote, urlparse
@@ -68,10 +67,6 @@ def applicationShouldOpenUntitledFile_(self, sender) -> bool:
 
     @objc_method
     def application_openFiles_(self, app, filenames) -> None:
-        # If there's no document types registered, we can't open files.
-        if not self.interface.document_types:
-            return
-
         for i in range(0, len(filenames)):
             filename = filenames[i]
             # If you start your Toga application as `python myapp.py` or
@@ -93,7 +88,14 @@ def application_openFiles_(self, app, filenames) -> None:
             else:
                 return
 
-            self.impl.open_document(str(fileURL.absoluteString))
+            # Convert a Cocoa fileURL to a Python file path.
+            path = Path(unquote(urlparse(str(fileURL.absoluteString)).path))
+            if hasattr(self.interface, "open"):
+                # If the user has provided an `open()` method on the app, use it.
+                self.interface.open(path)
+            elif self.interface.document_types:
+                # Use the document-based default implementation.
+                self.interface._open(path)
 
     @objc_method
     def selectMenuItem_(self, sender) -> None:
@@ -122,37 +124,36 @@ def __init__(self, interface):
         self.native = NSApplication.sharedApplication
         self.native.setApplicationIconImage(self.interface.icon._impl.native)
 
-        self.resource_path = os.path.dirname(
-            os.path.dirname(NSBundle.mainBundle.bundlePath)
-        )
+        self.resource_path = Path(NSBundle.mainBundle.bundlePath).parent.parent
 
         self.appDelegate = AppDelegate.alloc().init()
         self.appDelegate.impl = self
         self.appDelegate.interface = self.interface
         self.appDelegate.native = self.native
-        self.native.setDelegate_(self.appDelegate)
+        self.native.setDelegate(self.appDelegate)
 
         # Call user code to populate the main window
         self.interface._startup()
 
-        # Add any platform-specific app commands. This is done *after* startup to ensure
-        # that the main_window has been assigned, which informs which app commands are
-        # needed.
-        self.create_app_commands()
-
-        # Create the lookup table of menu and status items,
-        # then force the creation of the menus.
-        self._menu_groups = {}
-        self._menu_items = {}
-        self.create_menus()
-
     ######################################################################
     # App lifecycle
     ######################################################################
 
     def main_loop(self):
         self.loop.run_forever(lifecycle=CocoaLifecycle(self.native))
 
+    def finalize(self):
+        # Set up the lookup tables for menu items
+        self._menu_groups = {}
+        self._menu_items = {}
+
+        # Add any platform-specific app commands. This is done during finalization to
+        # ensure that the main_window has been assigned, which informs which app
+        # commands are needed.
+        self.create_app_commands()
+
+        self.create_menus()
+
     def set_main_window(self, window):
         # If it's a background app, don't display the app icon.
         if window == toga.App.BACKGROUND:
@@ -243,9 +244,11 @@ def create_app_commands(self):
             ),
         )
 
+        # Register the Apple HIG commands unless the app is using a simple Window
+        # as the main window, or it's a background app.
         if (
             isinstance(self.interface.main_window, toga.MainWindow)
-            or self.interface.main_window is None
+            and self.interface.main_window != toga.App.BACKGROUND
         ):
             self.interface.commands.add(
                 toga.Command(
@@ -371,12 +374,12 @@ def create_app_commands(self):
                 ),
             )
 
-        # If document types have been registered, provide file manipulation commands.
+        # Add a "New" menu item for each registered document type.
         if self.interface.document_types:
             for document_class in self.interface.document_types.values():
                 self.interface.commands.add(
                     toga.Command(
-                        self._menu_new_file(document_class),
+                        self._menu_new_document(document_class),
                         text=f"New {document_class.document_type}",
                         shortcut=(
                             toga.Key.MOD_1 + "n"
@@ -387,6 +390,10 @@ def create_app_commands(self):
                         section=0,
                     ),
                 )
+
+        # If there's a user-provided open() implementation, or there are registered
+        # document types, add an Open menu item.
+        if hasattr(self.interface, "open") or self.interface.document_types:
             self.interface.commands.add(
                 toga.Command(
                     self._menu_open_file,
@@ -396,6 +403,11 @@ def create_app_commands(self):
                     section=10,
                 ),
             )
+
+        # TODO: implement a save interface.
+        # If there are registered document types, add dummy Save/Save as/Save All menu
+        # items.
+        if self.interface.document_types:
             self.interface.commands.add(
                 toga.Command(
                     None,
@@ -432,7 +444,7 @@ def _menu_about(self, command, **kwargs):
     def _menu_quit(self, command, **kwargs):
         self.interface.on_exit()
 
-    def _menu_new_file(self, document_class):
+    def _menu_new_document(self, document_class):
         def new_file_handler(app, **kwargs):
             self.interface._new(document_class)
 
@@ -566,6 +578,13 @@ def show_about_dialog(self):
 
         self.native.orderFrontStandardAboutPanelWithOptions(options)
 
+    def beep(self):
+        NSBeep()
+
+    ######################################################################
+    # Platform utilities
+    ######################################################################
+
     def select_file(self, **kwargs):
         # FIXME This should be all we need; but for some reason, application types
         # aren't being registered correctly..
@@ -585,14 +604,3 @@ def select_file(self, **kwargs):
 
         # print("Untitled File opened?", panel.URLs)
         self.appDelegate.application(None, openFiles=panel.URLs)
-
-    def open_document(self, fileURL):
-        # Convert a cocoa fileURL to a file path.
-        fileURL = fileURL.rstrip("/")
-        path = Path(unquote(urlparse(fileURL).path))
-
-        # Create and show the document instance
-        self.interface._open(path)
-
-    def beep(self):
-        NSBeep()

cocoa/src/toga_cocoa/documents.py

@@ -27,7 +27,7 @@ def __init__(self, interface):
         self.native.interface = interface
         self.native.impl = self
 
-    def load(self):
+    def open(self):
         self.native.initWithContentsOfURL(
             NSURL.URLWithString(f"file://{quote(os.fsdecode(self.interface.path))}"),
             ofType=self.interface.document_type,

cocoa/src/toga_cocoa/window.py

@@ -161,6 +161,8 @@ def __init__(self, interface, title, position, size):
 
         self.set_title(title)
         self.set_size(size)
+
+        # Cascade the position of new windows.
         pos = 100 + len(App.app.windows) * 40
         self.set_position(position if position else (pos, pos))
 

core/src/toga/app.py

@@ -389,9 +389,6 @@ def __init__(
 
         self.factory.App(interface=self)
 
-        # Now that we have an impl, set the on_change handler for commands
-        self.commands.on_change = self._impl.create_menus
-
     ######################################################################
     # App properties
     ######################################################################
@@ -543,6 +540,15 @@ def _startup(self):
         # the app hasn't defined a main window.
         _ = self.main_window
 
+        # The App's impl is created when the app is constructed; however, on some
+        # platforms, (GTK, Windows), there are some activities that can't happen until
+        # the app manifests in some way (usually as a result of the app loop starting).
+        # Call the impl to allow for this finalization activity.
+        self._impl.finalize()
+
+        # Now that we have a finalized impl, set the on_change handler for commands
+        self.commands.on_change = self._impl.create_menus
+
     @property
     def main_window(self) -> MainWindow:
         """The main window for the app."""
@@ -717,7 +723,7 @@ def _open(self, path):
             raise ValueError(f"Don't know how to open documents of type {path.suffix}")
         else:
             document = DocType(app=self)
-            document.load(path)
+            document.open(path)
 
             self._documents.append(document)
             document.show()

core/src/toga/command.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from contextlib import contextmanager
 from typing import TYPE_CHECKING, Any, Protocol
 
 from toga.handlers import wrapped_handler
@@ -333,23 +332,6 @@ def clear(self):
         if self.on_change:
             self.on_change()
 
-    @contextmanager
-    def suspend_updates(self):
-        """Temporarily suspend ``on_change`` updates.
-
-        Inside this context manager, the ``on_change`` handler will not be
-        invoked if the CommandSet is modified. The ``on_change`` handler (if it
-        exists0 will be invoked when the context manager exits.
-        """
-        orig_on_change = self.on_change
-        self.on_change = None
-        try:
-            yield
-        finally:
-            self.on_change = orig_on_change
-            if self.on_change:
-                self.on_change()
-
     @property
     def app(self) -> App:
         return self._app

core/src/toga/documents.py

@@ -11,7 +11,7 @@
 
 
 class Document(ABC):
-    # Subclasses should override this definition this.
+    # Subclasses should override this definition.
     document_type = "Unknown Document"
 
     def __init__(self, app: App):
@@ -82,9 +82,9 @@ def show(self) -> None:
         """Show the :any:`main_window` for this document."""
         self.main_window.show()
 
-    def load(self, path: str | Path):
+    def open(self, path: str | Path):
         self._path = Path(path)
-        self._impl.load()
+        self._impl.open()
 
     @abstractmethod
     def create(self) -> None:

core/src/toga/window.py

@@ -367,7 +367,7 @@ def cleanup(window: Window, should_close: bool) -> None:
                     # Closing the window marked as the main window exits the app
                     self.app.on_exit()
                 elif self.app.main_window == self.app.BACKGROUND:
-                    # Otherwise (i.e., background apps)
+                    # In a background app, closing a window has no special handling.
                     window.close()
                 else:
                     # Otherwise: closing the *last* window exits the app (if platform

core/tests/test_documents.py

@@ -36,7 +36,7 @@ def test_create_document(app, path):
     assert doc.path is None
     assert doc.app == app
 
-    doc.load(path)
+    doc.open(path)
 
     assert doc.path == Path("/path/to/doc.mydoc")
 
@@ -51,8 +51,8 @@ def test_new_document(app):
     assert_action_performed(doc.main_window, "create Window")
     assert_action_performed(doc.main_window, "show")
 
-    # No load operation occurred
-    assert_action_not_performed(doc, "load")
+    # No open operation occurred
+    assert_action_not_performed(doc, "open")
     assert doc._data is None
 
 
@@ -70,8 +70,8 @@ def test_open_document(app):
     assert_action_performed(doc.main_window, "create Window")
     assert_action_performed(doc.main_window, "show")
 
-    # A load operation was performed
-    assert_action_performed(doc, "load document")
+    # A open operation was performed
+    assert_action_performed(doc, "open document")
     assert doc._data == "content"
 
 

dummy/src/toga_dummy/app.py

@@ -17,6 +17,9 @@ def __init__(self, interface):
         self._action("create App")
         self.interface._startup()
 
+    def finalize_create(self):
+        self._action("finalize creation")
+
     def create_menus(self):
         self._action("create App menus")