Introduce weak_handle methods on ModelContext and ViewContext

Co-Authored-By: Nathan Sobo <nathan@zed.dev>

crates/chat_panel/src/lib.rs

@@ -96,7 +96,7 @@ impl ChatPanel {
         });
 
         let mut message_list = ListState::new(0, Orientation::Bottom, 1000., {
-            let this = cx.handle().downgrade();
+            let this = cx.weak_handle();
             move |ix, cx| {
                 let this = this.upgrade(cx).unwrap().read(cx);
                 let message = this.active_channel.as_ref().unwrap().0.read(cx).message(ix);

crates/client/src/lib.rs

@@ -272,7 +272,7 @@ impl Client {
         let subscription_id = (TypeId::of::<T>(), Default::default());
         let client = self.clone();
         let mut state = self.state.write();
-        let model = cx.handle().downgrade();
+        let model = cx.weak_handle();
         let prev_extractor = state
             .entity_id_extractors
             .insert(subscription_id.0, Box::new(|_| Default::default()));
@@ -317,7 +317,7 @@ impl Client {
         let subscription_id = (TypeId::of::<T>(), remote_id);
         let client = self.clone();
         let mut state = self.state.write();
-        let model = cx.handle().downgrade();
+        let model = cx.weak_handle();
         state
             .entity_id_extractors
             .entry(subscription_id.0)

crates/editor/src/lib.rs

@@ -487,7 +487,7 @@ impl Editor {
             )
         });
         Self {
-            handle: cx.handle().downgrade(),
+            handle: cx.weak_handle(),
             buffer,
             display_map,
             selection_set_id,

crates/file_finder/src/lib.rs

@@ -286,7 +286,7 @@ impl FileFinder {
             .detach();
 
         Self {
-            handle: cx.handle().downgrade(),
+            handle: cx.weak_handle(),
             settings,
             project,
             query_editor,

crates/gpui/src/app.rs

@@ -2110,7 +2110,7 @@ impl<'a, T: Entity> ModelContext<'a, T> {
         S::Event: 'static,
         F: 'static + FnMut(&mut T, ModelHandle<S>, &S::Event, &mut ModelContext<T>),
     {
-        let subscriber = self.handle().downgrade();
+        let subscriber = self.weak_handle();
         self.app
             .subscribe_internal(handle, move |emitter, event, cx| {
                 if let Some(subscriber) = subscriber.upgrade(cx) {
@@ -2129,7 +2129,7 @@ impl<'a, T: Entity> ModelContext<'a, T> {
         S: Entity,
         F: 'static + FnMut(&mut T, ModelHandle<S>, &mut ModelContext<T>),
     {
-        let observer = self.handle().downgrade();
+        let observer = self.weak_handle();
         self.app.observe_internal(handle, move |observed, cx| {
             if let Some(observer) = observer.upgrade(cx) {
                 observer.update(cx, |observer, cx| {
@@ -2146,6 +2146,10 @@ impl<'a, T: Entity> ModelContext<'a, T> {
         ModelHandle::new(self.model_id, &self.app.cx.ref_counts)
     }
 
+    pub fn weak_handle(&self) -> WeakModelHandle<T> {
+        WeakModelHandle::new(self.model_id)
+    }
+
     pub fn spawn<F, Fut, S>(&self, f: F) -> Task<S>
     where
         F: FnOnce(ModelHandle<T>, AsyncAppContext) -> Fut,
@@ -2162,7 +2166,7 @@ impl<'a, T: Entity> ModelContext<'a, T> {
         Fut: 'static + Future<Output = S>,
         S: 'static,
     {
-        let handle = self.handle().downgrade();
+        let handle = self.weak_handle();
         self.app.spawn(|cx| f(handle, cx))
     }
 }
@@ -2241,6 +2245,10 @@ impl<'a, T: View> ViewContext<'a, T> {
         ViewHandle::new(self.window_id, self.view_id, &self.app.cx.ref_counts)
     }
 
+    pub fn weak_handle(&self) -> WeakViewHandle<T> {
+        WeakViewHandle::new(self.window_id, self.view_id)
+    }
+
     pub fn window_id(&self) -> usize {
         self.window_id
     }
@@ -2336,7 +2344,7 @@ impl<'a, T: View> ViewContext<'a, T> {
         H: Handle<E>,
         F: 'static + FnMut(&mut T, H, &E::Event, &mut ViewContext<T>),
     {
-        let subscriber = self.handle().downgrade();
+        let subscriber = self.weak_handle();
         self.app
             .subscribe_internal(handle, move |emitter, event, cx| {
                 if let Some(subscriber) = subscriber.upgrade(cx) {
@@ -2356,7 +2364,7 @@ impl<'a, T: View> ViewContext<'a, T> {
         H: Handle<E>,
         F: 'static + FnMut(&mut T, H, &mut ViewContext<T>),
     {
-        let observer = self.handle().downgrade();
+        let observer = self.weak_handle();
         self.app.observe_internal(handle, move |observed, cx| {
             if let Some(observer) = observer.upgrade(cx) {
                 observer.update(cx, |observer, cx| {
@@ -2400,7 +2408,7 @@ impl<'a, T: View> ViewContext<'a, T> {
         Fut: 'static + Future<Output = S>,
         S: 'static,
     {
-        let handle = self.handle().downgrade();
+        let handle = self.weak_handle();
         self.app.spawn(|cx| f(handle, cx))
     }
 }

crates/gpui/src/views/select.rs

@@ -42,7 +42,7 @@ impl Select {
         render_item: F,
     ) -> Self {
         Self {
-            handle: cx.handle().downgrade(),
+            handle: cx.weak_handle(),
             render_item: Box::new(render_item),
             selected_item_ix: 0,
             item_count,

crates/project_panel/src/lib.rs

@@ -108,7 +108,7 @@ impl ProjectPanel {
                 visible_entries: Default::default(),
                 expanded_dir_ids: Default::default(),
                 selection: None,
-                handle: cx.handle().downgrade(),
+                handle: cx.weak_handle(),
             };
             this.update_visible_entries(None, cx);
             this