add optional dependency variants of selectors and effects

packages/signals/examples/dependancies.rs

@@ -0,0 +1,38 @@
+#![allow(non_snake_case)]
+
+use dioxus::prelude::*;
+use dioxus_signals::*;
+
+fn main() {
+    dioxus_desktop::launch(app);
+}
+
+fn app(cx: Scope) -> Element {
+    let signal = use_signal(cx, || 0);
+
+    use_future!(cx, || async move {
+        loop {
+            tokio::time::sleep(std::time::Duration::from_secs(1)).await;
+            *signal.write() += 1;
+        }
+    });
+
+    let local_state = use_state(cx, || 0);
+    let computed =
+        use_selector_with_dependencies(cx, (local_state.get(),), move |(local_state,)| {
+            local_state * 2 + signal.value()
+        });
+    println!("Running app");
+
+    render! {
+        button {
+            onclick: move |_| {
+                local_state.set(local_state.get() + 1);
+            },
+            "Add one"
+        }
+        div {
+            "{computed}"
+        }
+    }
+}