remove extra generic from SignalMap

packages/signals/src/map.rs

@@ -4,18 +4,16 @@ use std::cell::Ref;
 use std::fmt::Debug;
 use std::fmt::Display;
 
-/// A signal that can only be read from.
-pub struct SignalMap<T: 'static, U: ?Sized> {
-    inner: Signal<T>,
-    mapping: fn(&T) -> &U,
+/// A read only signal that has been mapped to a new type.
+pub struct SignalMap<U: ?Sized> {
+    mapping: Box<dyn Fn() -> Ref<'static, U>>,
 }
 
 impl<T: 'static, U: ?Sized> SignalMap<T, U> {
-    /// Create a new read-only signal.
+    /// Create a new mapped signal.
     pub fn new(signal: Signal<T>, mapping: fn(&T) -> &U) -> Self {
         Self {
-            inner: signal,
-            mapping,
+            mapping: Box::new(move || Ref::map(signal.read(), |v| (mapping)(v))),
         }
     }
 
@@ -26,56 +24,56 @@ impl<T: 'static, U: ?Sized> SignalMap<T, U> {
 
     /// Get the current value of the signal. This will subscribe the current scope to the signal.
     pub fn read(&self) -> Ref<U> {
-        Ref::map(self.inner.read(), |v| (self.mapping)(v))
+        (self.mapping)()
     }
 
     /// Run a closure with a reference to the signal's value.
     pub fn with<O>(&self, f: impl FnOnce(&U) -> O) -> O {
-        self.inner.with(|v| f((self.mapping)(v)))
+        f(&*self.read())
     }
 }
 
-impl<T: 'static, U: ?Sized + Clone> SignalMap<T, U> {
+impl<U: ?Sized + Clone> SignalMap<U> {
     /// Get the current value of the signal. This will subscribe the current scope to the signal.
     pub fn value(&self) -> U {
         self.read().clone()
     }
 }
 
-impl<T: 'static, U: ?Sized> PartialEq for SignalMap<T, U> {
+impl<U: ?Sized> PartialEq for SignalMap<U> {
     fn eq(&self, other: &Self) -> bool {
         self.inner == other.inner
     }
 }
 
-impl<T, U> std::clone::Clone for SignalMap<T, U> {
+impl<U> std::clone::Clone for SignalMap<U> {
     fn clone(&self) -> Self {
         *self
     }
 }
 
-impl<T, U> Copy for SignalMap<T, U> {}
+impl<U> Copy for SignalMap<U> {}
 
-impl<T: 'static, U: ?Sized + Display> Display for SignalMap<T, U> {
+impl<U: ?Sized + Display> Display for SignalMap<U> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.with(|v| Display::fmt(v, f))
     }
 }
 
-impl<T: 'static, U: ?Sized + Debug> Debug for SignalMap<T, U> {
+impl<U: ?Sized + Debug> Debug for SignalMap<U> {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         self.with(|v| Debug::fmt(v, f))
     }
 }
 
-impl<T: 'static, U> SignalMap<T, Vec<U>> {
+impl<U> SignalMap<Vec<U>> {
     /// Read a value from the inner vector.
-    pub fn get(&self, index: usize) -> Option<Ref<'_, U>> {
+    pub fn get(&self, index: usize) -> Option<Ref<'static, U>> {
         Ref::filter_map(self.read(), |v| v.get(index)).ok()
     }
 }
 
-impl<T, U: Clone + 'static> SignalMap<T, Option<U>> {
+impl<U: Clone + 'static> SignalMap<Option<U>> {
     /// Unwraps the inner value and clones it.
     pub fn unwrap(&self) -> U
     where
@@ -85,7 +83,7 @@ impl<T, U: Clone + 'static> SignalMap<T, Option<U>> {
     }
 
     /// Attemps to read the inner value of the Option.
-    pub fn as_ref(&self) -> Option<Ref<'_, U>> {
+    pub fn as_ref(&self) -> Option<Ref<'static, U>> {
         Ref::filter_map(self.read(), |v| v.as_ref()).ok()
     }
 }