Add clear() method to RadioSet

src/textual/widgets/_radio_set.py

@@ -106,7 +106,8 @@ class Changed(Message):
         ALLOW_SELECTOR_MATCH = {"pressed"}
         """Additional message attributes that can be used with the [`on` decorator][textual.on]."""
 
-        def __init__(self, radio_set: RadioSet, pressed: RadioButton) -> None:
+        def __init__(self, radio_set: RadioSet, pressed: RadioButton | None) -> None: # None = cleared state 
+
             """Initialise the message.
 
             Args:
@@ -247,7 +248,12 @@ def _on_radio_set_changed(self, event: RadioSet.Changed) -> None:
         This handler ensures that, when a button is pressed, it's also the
         selected button.
         """
-        self._selected = event.index
+        if event.index >= 0:
+            self._selected = event.index
+        else:
+            # cleared state - avoid triggering watcher
+            with self.prevent(RadioSet.Changed):
+                self._selected = None
 
     async def _on_click(self, _: Click) -> None:
         """Handle a click on or within the radio set.
@@ -299,6 +305,30 @@ def action_toggle_button(self) -> None:
             button = self._nodes[self._selected]
             assert isinstance(button, RadioButton)
             button.toggle()
+
+    def clear(self) -> None:
+        """Clear the radio set so that no button is pressed.
+
+    This returns the RadioSet to its initial unset state, useful for
+    survey/questionnaire interfaces where "no response" is a valid state.
+    See: https://github.com/Textualize/textual/issues/6197
+    """
+        # turn off all buttons
+        with self.prevent(RadioButton.Changed):
+            for button in self.query(RadioButton):
+                button.value = False
+
+        self._pressed_button = None
+        self.query(RadioButton).remove_class("-selected")
+
+        # set to None without triggering the watcher
+        with self.prevent(RadioSet.Changed):
+            self._selected = None
+
+        self.post_message(self.Changed(self, None))
+        self.refresh()
+
+
 
     def _scroll_to_selected(self) -> None:
         """Ensure that the selected button is in view."""

tests/test_radio_set_clear.py

@@ -0,0 +1,122 @@
+from textual.app import App, ComposeResult
+from textual.widgets import RadioSet, RadioButton
+
+
+class RadioSetTestApp(App):
+    def compose(self) -> ComposeResult:
+        yield RadioSet(
+            RadioButton("One"),
+            RadioButton("Two"),
+            RadioButton("Three"),
+        )
+
+
+async def test_radioset_clear():
+    """clear() should remove all selections"""
+    app = RadioSetTestApp()
+
+    async with app.run_test() as pilot:
+        rs = app.query_one(RadioSet)
+        buttons = list(rs.query(RadioButton))
+        rb1, rb2, rb3 = buttons
+
+        await pilot.pause()
+
+        # press second button
+        rb2.value = True
+        await pilot.pause()
+
+        assert rs.pressed_button is rb2
+        assert rs.pressed_index == 1
+        assert rb2.value is True
+
+        # now clear it
+        rs.clear()
+        await pilot.pause()
+
+        assert rs.pressed_button is None
+        assert rs.pressed_index == -1
+
+        for rb in buttons:
+            assert rb.value is False
+
+
+async def test_clear_empty_radioset():
+    """calling clear on empty radioset shouldn't crash"""
+
+    class EmptyApp(App):
+        def compose(self) -> ComposeResult:
+            yield RadioSet()
+
+    app = EmptyApp()
+
+    async with app.run_test() as pilot:
+        rs = app.query_one(RadioSet)
+        await pilot.pause()
+
+        rs.clear()  # shouldn't error
+        await pilot.pause()
+
+        assert rs.pressed_button is None
+        assert rs.pressed_index == -1
+
+
+async def test_clear_twice():
+    """clearing multiple times should work fine"""
+
+    class TestApp(App):
+        def compose(self) -> ComposeResult:
+            yield RadioSet(
+                RadioButton("One"),
+                RadioButton("Two"),
+            )
+
+    app = TestApp()
+
+    async with app.run_test() as pilot:
+        rs = app.query_one(RadioSet)
+        btns = list(rs.query(RadioButton))
+        await pilot.pause()
+
+        btns[0].value = True
+        await pilot.pause()
+        assert rs.pressed_button is btns[0]
+
+        rs.clear()
+        await pilot.pause()
+        assert rs.pressed_button is None
+
+        # clear again - should still work
+        rs.clear()
+        await pilot.pause()
+        assert rs.pressed_button is None
+        assert rs.pressed_index == -1
+
+
+async def test_can_select_after_clear():
+    """after clearing, we should be able to select buttons again"""
+
+    class TestApp(App):
+        def compose(self) -> ComposeResult:
+            yield RadioSet(
+                RadioButton("Option A"),
+                RadioButton("Option B"),
+            )
+
+    app = TestApp()
+
+    async with app.run_test() as pilot:
+        rs = app.query_one(RadioSet)
+        btns = list(rs.query(RadioButton))
+        await pilot.pause()
+
+        rs.clear()
+        await pilot.pause()
+        assert rs.pressed_button is None
+
+        # should be able to select again
+        btns[1].value = True
+        await pilot.pause()
+
+        assert rs.pressed_button is btns[1]
+        assert rs.pressed_index == 1