fix subscriptions in events

packages/signals/src/effect.rs

@@ -0,0 +1,52 @@
+use dioxus_core::prelude::*;
+
+use crate::CopyValue;
+
+#[derive(Default, Clone, Copy)]
+pub(crate) struct EffectStack {
+    pub(crate) effects: CopyValue<Vec<Effect>>,
+}
+
+pub(crate) fn get_effect_stack() -> EffectStack {
+    match consume_context() {
+        Some(rt) => rt,
+        None => {
+            let store = EffectStack::default();
+            provide_root_context(store).expect("in a virtual dom")
+        }
+    }
+}
+
+#[derive(Copy, Clone, PartialEq)]
+pub struct Effect {
+    callback: CopyValue<Box<dyn FnMut()>>,
+}
+
+impl Effect {
+    pub(crate) fn current() -> Option<Self> {
+        get_effect_stack().effects.read().last().copied()
+    }
+
+    pub fn new(callback: impl FnMut() + 'static) -> Self {
+        let myself = Self {
+            callback: CopyValue::new(Box::new(callback)),
+        };
+
+        myself.try_run();
+
+        myself
+    }
+
+    /// Run the effect callback immediately. Returns `true` if the effect was run. Returns `false` is the effect is dead.
+    pub fn try_run(&self) {
+        if let Some(mut callback) = self.callback.try_write() {
+            {
+                get_effect_stack().effects.write().push(*self);
+            }
+            callback();
+            {
+                get_effect_stack().effects.write().pop();
+            }
+        }
+    }
+}