Revert lazy import of documents and statusicons, and work around …

…MicroPython's inability to set custom attributes on functions

core/src/toga/app.py

@@ -10,20 +10,20 @@
 
 from toga.command import Command, CommandSet
 from toga.constants import WindowState
+from toga.documents import Document, DocumentSet
 from toga.handlers import simple_handler, wrapped_handler
 from toga.icons import Icon
 from toga.paths import Paths
 from toga.platform import get_platform_factory
+from toga.statusicons import StatusIconSet
 from toga.window import MainWindow, Window, WindowSet
 
 if TYPE_CHECKING:
     from toga.dialogs import Dialog
-    from toga.documents import Document, DocumentSet
     from toga.hardware.camera import Camera
     from toga.hardware.location import Location
     from toga.icons import IconContentT
     from toga.screens import Screen
-    from toga.statusicons import StatusIconSet
     from toga.widgets.base import Widget
 
 # Make sure deprecation warnings are shown by default
@@ -316,7 +316,10 @@ def __init__(
             self.icon = icon
 
         # Set up the document types and collection of documents being managed.
-        self._document_types = [] if document_types is None else document_types
+        self._documents = DocumentSet(
+            self,
+            types=[] if document_types is None else document_types,
+        )
 
         # Install the lifecycle handlers. If passed in as an argument, or assigned using
         # `app.on_event = my_handler`, the event handler will take the app as the first
@@ -335,6 +338,7 @@ def __init__(
         # We need the command set to exist so that startup et al. can add commands;
         # but we don't have an impl yet, so we can't set the on_change handler
         self._commands = CommandSet()
+        self._status_icons = StatusIconSet()
 
         self._startup_method = startup
 
@@ -578,22 +582,22 @@ def _create_standard_commands(self):
         ]:
             self.commands.add(Command.standard(self, cmd_id))
 
-        if self._document_types:
-            default_document_type = self._document_types[0]
+        if self.documents.types:
+            default_document_type = self.documents.types[0]
             command = Command.standard(
                 self,
                 Command.NEW,
                 action=simple_handler(self.documents.new, default_document_type),
             )
             if command:
-                if len(self._document_types) == 1:
+                if len(self.documents.types) == 1:
                     # There's only 1 document type. The new command can be used as is.
                     self.commands.add(command)
                 else:
                     # There's more than one document type. Create a new command for each
                     # document type, updating the title of the command to disambiguate,
                     # and modifying the shortcut, order and ID of the document types 2+
-                    for i, document_class in enumerate(self._document_types):
+                    for i, document_class in enumerate(self.documents.types):
                         command = Command.standard(
                             self,
                             Command.NEW,
@@ -628,16 +632,16 @@ def _create_initial_windows(self):
         """
         # Process command line arguments if the backend doesn't handle them
         if not self._impl.HANDLES_COMMAND_LINE:
-            if self._document_types:
+            if self.documents.types:
                 for filename in sys.argv[1:]:
                     self._open_initial_document(filename)
 
         # Ensure there is at least one window
         if self.main_window is None and len(self.windows) == 0:
-            if self._document_types:
+            if self.documents.types:
                 if self._impl.CLOSE_ON_LAST_WINDOW:
                     # Pass in the first document type as the default
-                    self.documents.new(self._document_types[0])
+                    self.documents.new(self.documents.types[0])
                 else:
                     self.loop.run_until_complete(self.documents.request_open())
             else:
@@ -732,14 +736,7 @@ def commands(self) -> CommandSet:
     @property
     def documents(self) -> DocumentSet:
         """The list of documents associated with this app."""
-        try:
-            return self._documents
-        except AttributeError:
-            # Initialize on first access.
-            from .documents import DocumentSet
-
-            self._documents = DocumentSet(self, self._document_types)
-            return self._documents
+        return self._documents
 
     @property
     def location(self) -> Location:
@@ -773,14 +770,7 @@ def screens(self) -> list[Screen]:
     @property
     def status_icons(self) -> StatusIconSet:
         """The status icons displayed by the app."""
-        try:
-            return self._status_icons
-        except AttributeError:
-            # Initialize on first access.
-            from .statusicons import StatusIconSet
-
-            self._status_icons = StatusIconSet()
-            return self._status_icons
+        return self._status_icons
 
     @property
     def widgets(self) -> WidgetRegistry:
@@ -1064,6 +1054,6 @@ def document_types(self) -> dict[str, type[Document]]:
         )
         return {
             extension: doc_type
-            for doc_type in self._document_types
+            for doc_type in self.documents.types
             for extension in doc_type.extensions
         }

core/src/toga/documents.py

@@ -9,7 +9,6 @@
 
 import toga
 from toga import dialogs
-from toga.handlers import overridable, overridden
 from toga.window import MainWindow, Window
 
 if TYPE_CHECKING:
@@ -117,13 +116,15 @@ def open(self, path: str | Path):
     def save(self, path: str | Path | None = None):
         """Save the document as a file.
 
-        If a path is provided, and the :meth:`~toga.Document.write` method has been
-        overwritten, the path for the document will be updated. Otherwise, the existing
-        path will be used.
+        If a path is provided, the path for the document will be updated. Otherwise, the
+        existing path will be used.
+
+        If the :meth:`~toga.Document.write` method has not been implemented, this method
+        is a no-op.
 
         :param path: If provided, the new file name for the document.
         """
-        if overridden(self.write):
+        if self._writable():
             if path:
                 self._path = Path(path).absolute()
                 # Re-set the title of the document with the new path
@@ -132,6 +133,10 @@ def save(self, path: str | Path | None = None):
             # Clear the modification flag.
             self.modified = False
 
+    # A document is writable if its class overrides the `write` method.
+    def _writable(self):
+        return getattr(type(self), "write") is not Document.write
+
     def show(self) -> None:
         """Show the visual representation for this document."""
         self.main_window.show()
@@ -162,7 +167,6 @@ def read(self) -> None:
         :attr:`~toga.Document.path`, and populate the document window.
         """
 
-    @overridable
     def write(self) -> None:
         """Persist a representation of the current state of the document.
 
@@ -452,13 +456,13 @@ def _close(self):
     async def save(self):
         """Save the document associated with this window.
 
-        If the document associated with a window hasn't been saved before, and the
-        document type defines a :meth:`~toga.Document.write` method, the user will be
-        prompted to provide a filename.
+        If the document associated with a window hasn't been saved before, the user will
+        be prompted to provide a filename.
 
-        :returns: True if the save was successful; False if the save was aborted.
+        :returns: True if the save was successful; False if the save was aborted, or the
+            document type doesn't define a :meth:`~toga.Document.write` method.
         """
-        if overridden(self.doc.write):
+        if self.doc._writable():
             if self.doc.path:
                 # Document has been saved previously; save using that filename.
                 self.doc.save()
@@ -471,12 +475,12 @@ async def save_as(self):
         """Save the document associated with this window under a new filename.
 
         The default implementation will prompt the user for a new filename, then save
-        the document with that new filename. If the document type doesn't define a
-        :meth:`~toga.Document.write` method, the save-as request will be ignored.
+        the document with that new filename.
 
-        :returns: True if the save was successful; False if the save was aborted.
+        :returns: True if the save was successful; False if the save was aborted, or the
+            document type doesn't define a :meth:`~toga.Document.write` method.
         """
-        if overridden(self.doc.write):
+        if self.doc._writable():
             suggested_path = (
                 self.doc.path if self.doc.path else f"Untitled.{self.doc.extensions[0]}"
             )

core/src/toga/handlers.py

@@ -29,21 +29,6 @@
     WrappedHandlerT: TypeAlias = Callable[..., object]
 
 
-def overridable(method: T) -> T:
-    """Decorate the method as being user-overridable"""
-    method._overridden = True
-    return method
-
-
-def overridden(coroutine_or_method: Callable) -> bool:
-    """Has the user overridden this method?
-
-    This is based on the method *not* having a ``_overridden`` attribute. Overridable
-    default methods have this attribute; user-defined method will not.
-    """
-    return not hasattr(coroutine_or_method, "_overridden")
-
-
 class NativeHandler:
     def __init__(self, handler: Callable[..., object]):
         self.native = handler