xilem_core: return element in View::rebuild

xilem/src/view/button.rs

@@ -2,10 +2,8 @@
 // SPDX-License-Identifier: Apache-2.0
 
 use crate::{core::View, Pod};
-use masonry::{
-    widget::{self, WidgetMut},
-    ArcStr,
-};
+use masonry::{widget, ArcStr};
+use xilem_core::Mut;
 
 use crate::{MessageResult, ViewCtx, ViewId};
 
@@ -35,24 +33,25 @@ where
         ctx.with_leaf_action_widget(|_| Pod::new(widget::Button::new(self.label.clone())))
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         _: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<widget::Button>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Button>>,
+    ) -> Mut<'el, Pod<widget::Button>> {
         if prev.label != self.label {
             element.set_text(self.label.clone());
             ctx.mark_changed();
         }
+        element
     }
 
     fn teardown(
         &self,
         _: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        element: <Self::Element as xilem_core::ViewElement>::Mut<'_>,
+        element: Mut<'_, Pod<widget::Button>>,
     ) {
         ctx.teardown_leaf(element);
     }

xilem/src/view/checkbox.rs

@@ -1,10 +1,8 @@
 // Copyright 2024 the Xilem Authors
 // SPDX-License-Identifier: Apache-2.0
 
-use masonry::{
-    widget::{self, WidgetMut},
-    ArcStr,
-};
+use masonry::{widget, ArcStr};
+use xilem_core::Mut;
 
 use crate::{MessageResult, Pod, View, ViewCtx, ViewId};
 
@@ -45,13 +43,13 @@ where
         })
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         (): &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<'_, widget::Checkbox>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Checkbox>>,
+    ) -> Mut<'el, Pod<widget::Checkbox>> {
         if prev.label != self.label {
             element.set_text(self.label.clone());
             ctx.mark_changed();
@@ -60,13 +58,14 @@ where
             element.set_checked(self.checked);
             ctx.mark_changed();
         }
+        element
     }
 
     fn teardown(
         &self,
         (): &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        element: WidgetMut<'_, widget::Checkbox>,
+        element: Mut<'_, Pod<widget::Checkbox>>,
     ) {
         ctx.teardown_leaf(element);
     }

xilem/src/view/flex.rs

@@ -7,7 +7,7 @@ use masonry::{
     widget::{self, Axis, CrossAxisAlignment, MainAxisAlignment, WidgetMut},
     Widget,
 };
-use xilem_core::{AppendVec, ElementSplice, View, ViewSequence};
+use xilem_core::{AppendVec, ElementSplice, Mut, View, ViewSequence};
 
 use crate::{Pod, ViewCtx};
 
@@ -75,13 +75,13 @@ where
         (Pod::new(widget), seq_state)
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         view_state: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<widget::Flex>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Flex>>,
+    ) -> Mut<'el, Pod<widget::Flex>> {
         if prev.axis != self.axis {
             element.set_direction(self.axis);
             ctx.mark_changed();
@@ -102,24 +102,25 @@ where
         let mut splice = FlexSplice {
             // Skip the initial spacer which is always present
             ix: 1,
-            element,
+            element: &mut element,
             scratch: AppendVec::default(),
         };
         self.sequence
             .seq_rebuild(&prev.sequence, view_state, ctx, &mut splice);
         debug_assert!(splice.scratch.into_inner().is_empty());
+        element
     }
 
     fn teardown(
         &self,
         view_state: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        element: <Self::Element as xilem_core::ViewElement>::Mut<'_>,
+        mut element: Mut<'_, Pod<widget::Flex>>,
     ) {
         let mut splice = FlexSplice {
             // Skip the initial spacer which is always present
             ix: 1,
-            element,
+            element: &mut element,
             scratch: AppendVec::default(),
         };
         self.sequence.seq_teardown(view_state, ctx, &mut splice);
@@ -138,13 +139,13 @@ where
     }
 }
 
-struct FlexSplice<'w> {
+struct FlexSplice<'f, 'w> {
     ix: usize,
-    element: WidgetMut<'w, widget::Flex>,
+    element: &'f mut WidgetMut<'w, widget::Flex>,
     scratch: AppendVec<Pod<Box<dyn Widget>>>,
 }
 
-impl ElementSplice<Pod<Box<dyn Widget>>> for FlexSplice<'_> {
+impl<'f> ElementSplice<Pod<Box<dyn Widget>>> for FlexSplice<'f, '_> {
     fn insert(&mut self, element: Pod<Box<dyn masonry::Widget>>) {
         self.element.insert_child_pod(self.ix, element.inner);
         // Insert a spacer after the child

xilem/src/view/label.rs

@@ -1,10 +1,8 @@
 // Copyright 2024 the Xilem Authors
 // SPDX-License-Identifier: Apache-2.0
 
-use masonry::{
-    widget::{self, WidgetMut},
-    ArcStr,
-};
+use masonry::{widget, ArcStr};
+use xilem_core::Mut;
 
 use crate::{Color, MessageResult, Pod, TextAlignment, View, ViewCtx, ViewId};
 
@@ -55,13 +53,13 @@ impl<State, Action> View<State, Action, ViewCtx> for Label {
         (widget_pod, ())
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         (): &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<'_, widget::Label>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Label>>,
+    ) -> Mut<'el, Pod<widget::Label>> {
         if prev.label != self.label {
             element.set_text(self.label.clone());
             ctx.mark_changed();
@@ -78,10 +76,10 @@ impl<State, Action> View<State, Action, ViewCtx> for Label {
             element.set_alignment(self.alignment);
             ctx.mark_changed();
         }
+        element
     }
 
-    fn teardown(&self, (): &mut Self::ViewState, _: &mut ViewCtx, _: WidgetMut<'_, widget::Label>) {
-    }
+    fn teardown(&self, (): &mut Self::ViewState, _: &mut ViewCtx, _: Mut<'_, Pod<widget::Label>>) {}
 
     fn message(
         &self,

xilem/src/view/prose.rs

@@ -1,11 +1,8 @@
 // Copyright 2024 the Xilem Authors
 // SPDX-License-Identifier: Apache-2.0
 
-use masonry::{
-    text2::TextBrush,
-    widget::{self, WidgetMut},
-    ArcStr,
-};
+use masonry::{text2::TextBrush, widget, ArcStr};
+use xilem_core::Mut;
 
 use crate::{Color, MessageResult, Pod, TextAlignment, View, ViewCtx, ViewId};
 
@@ -57,13 +54,13 @@ impl<State, Action> View<State, Action, ViewCtx> for Prose {
         (widget_pod, ())
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         (): &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<'_, widget::Prose>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Prose>>,
+    ) -> Mut<'el, Pod<widget::Prose>> {
         if prev.label != self.label {
             element.set_text(self.label.clone());
             ctx.mark_changed();
@@ -76,10 +73,10 @@ impl<State, Action> View<State, Action, ViewCtx> for Prose {
             element.set_alignment(self.alignment);
             ctx.mark_changed();
         }
+        element
     }
 
-    fn teardown(&self, (): &mut Self::ViewState, _: &mut ViewCtx, _: WidgetMut<'_, widget::Prose>) {
-    }
+    fn teardown(&self, (): &mut Self::ViewState, _: &mut ViewCtx, _: Mut<'_, Pod<widget::Prose>>) {}
 
     fn message(
         &self,

xilem/src/view/textbox.rs

@@ -1,11 +1,8 @@
 // Copyright 2024 the Xilem Authors
 // SPDX-License-Identifier: Apache-2.0
 
-use masonry::{
-    text2::TextBrush,
-    widget::{self, WidgetMut},
-};
-use xilem_core::View;
+use masonry::{text2::TextBrush, widget};
+use xilem_core::{Mut, View};
 
 use crate::{Color, MessageResult, Pod, TextAlignment, ViewCtx, ViewId};
 
@@ -80,13 +77,13 @@ impl<State: 'static, Action: 'static> View<State, Action, ViewCtx> for Textbox<S
         })
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         _: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        mut element: WidgetMut<widget::Textbox>,
-    ) {
+        mut element: Mut<'el, Pod<widget::Textbox>>,
+    ) -> Mut<'el, Pod<widget::Textbox>> {
         // Unlike the other properties, we don't compare to the previous value;
         // instead, we compare directly to the element's text. This is to handle
         // cases like "Previous data says contents is 'fooba', user presses 'r',
@@ -107,13 +104,14 @@ impl<State: 'static, Action: 'static> View<State, Action, ViewCtx> for Textbox<S
             element.set_alignment(self.alignment);
             ctx.mark_changed();
         }
+        element
     }
 
     fn teardown(
         &self,
         _: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        element: <Self::Element as xilem_core::ViewElement>::Mut<'_>,
+        element: Mut<'_, Pod<widget::Textbox>>,
     ) {
         ctx.teardown_leaf(element);
     }

xilem_core/examples/filesystem.rs

@@ -3,7 +3,9 @@
 
 use std::{io::stdin, path::PathBuf};
 
-use xilem_core::{AnyElement, AnyView, SuperElement, View, ViewElement, ViewId, ViewPathTracker};
+use xilem_core::{
+    AnyElement, AnyView, Mut, SuperElement, View, ViewElement, ViewId, ViewPathTracker,
+};
 
 #[derive(Debug)]
 enum State {
@@ -103,7 +105,7 @@ impl SuperElement<FsPath> for FsPath {
 
     fn with_downcast_val<R>(
         this: Self::Mut<'_>,
-        f: impl FnOnce(<FsPath as ViewElement>::Mut<'_>) -> R,
+        f: impl FnOnce(Mut<'_, FsPath>) -> R,
     ) -> (Self::Mut<'_>, R) {
         let ret = f(this);
         (this, ret)
@@ -155,28 +157,29 @@ impl<State, Action> View<State, Action, ViewCtx> for File {
         (path.into(), ())
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         prev: &Self,
         _view_state: &mut Self::ViewState,
         ctx: &mut ViewCtx,
-        element: <Self::Element as xilem_core::ViewElement>::Mut<'_>,
-    ) {
+        element: Mut<'el, FsPath>,
+    ) -> Mut<'el, FsPath> {
         if prev.name != self.name {
             let new_path = ctx.current_folder_path.join(&*self.name);
             let _ = std::fs::rename(&element, &new_path);
             *element = new_path;
         }
         if self.contents != prev.contents {
-            let _ = std::fs::write(element, self.contents.as_bytes());
+            let _ = std::fs::write(&element, self.contents.as_bytes());
         }
+        element
     }
 
     fn teardown(
         &self,
         _view_state: &mut Self::ViewState,
         _ctx: &mut ViewCtx,
-        element: <Self::Element as xilem_core::ViewElement>::Mut<'_>,
+        element: Mut<'_, Self::Element>,
     ) {
         let _ = std::fs::remove_file(element);
     }

xilem_core/examples/user_interface.rs

@@ -6,7 +6,7 @@
 use core::any::Any;
 
 use xilem_core::{
-    DynMessage, MessageResult, SuperElement, View, ViewElement, ViewId, ViewPathTracker,
+    DynMessage, MessageResult, Mut, SuperElement, View, ViewElement, ViewId, ViewPathTracker,
 };
 
 pub fn app_logic(_: &mut u32) -> impl WidgetView<u32> {
@@ -57,21 +57,22 @@ impl<State, Action> View<State, Action, ViewCtx> for Button {
         )
     }
 
-    fn rebuild(
+    fn rebuild<'el>(
         &self,
         _prev: &Self,
         _view_state: &mut Self::ViewState,
         _ctx: &mut ViewCtx,
-        _element: <Self::Element as ViewElement>::Mut<'_>,
-    ) {
+        element: Mut<'el, WidgetPod<ButtonWidget>>,
+    ) -> Mut<'el, WidgetPod<ButtonWidget>> {
         // Nothing to do
+        element
     }
 
     fn teardown(
         &self,
         _view_state: &mut Self::ViewState,
         _ctx: &mut ViewCtx,
-        _element: <Self::Element as ViewElement>::Mut<'_>,
+        _element: Mut<'_, WidgetPod<ButtonWidget>>,
     ) {
         // Nothing to do
     }