Relax Fn requirements (#2620)

crates/burn-core/src/module/param/base.rs

@@ -72,14 +72,14 @@ pub trait Parameter: Clone + core::fmt::Debug + Send {
 
 #[allow(clippy::type_complexity)]
 struct Uninitialized<P: Parameter> {
-    init: Box<dyn Fn(&P::Device, bool) -> P + Send>,
+    init: Box<dyn FnOnce(&P::Device, bool) -> P + Send>,
     device: P::Device,
     is_require_grad: bool,
 }
 
 impl<P: Parameter> Uninitialized<P> {
-    fn initialize(&self) -> P {
-        let init = &self.init;
+    fn initialize(self) -> P {
+        let init = self.init;
         init(&self.device, self.is_require_grad)
     }
 }
@@ -97,7 +97,7 @@ impl<T: Parameter> Param<T> {
     /// Create a new parameter that is not already initialized.
     pub fn uninitialized<F>(id: ParamId, init: F, device: T::Device, is_require_grad: bool) -> Self
     where
-        F: Fn(&T::Device, bool) -> T + Send + 'static,
+        F: FnOnce(&T::Device, bool) -> T + Send + 'static,
     {
         Self {
             id,
@@ -120,12 +120,8 @@ impl<T: Parameter> Param<T> {
                     .expect("Should have an initialization when no state provided.")
                     .write()
                     .unwrap();
-                let state = result.as_ref().expect("Should exist when not initialized");
-                let tensor = state.initialize();
-
-                *result = None;
-
-                tensor
+                let state = result.take().expect("Should exist when not initialized");
+                state.initialize()
             })
             .clone()
     }
@@ -145,7 +141,7 @@ impl<T: Parameter> Param<T> {
     }
 
     /// Execute the given function on the inner value.
-    pub fn map<F: Fn(T) -> T>(self, func: F) -> Self {
+    pub fn map<F: FnOnce(T) -> T>(self, func: F) -> Self {
         let (id, tensor) = self.consume();
         let tensor = func(tensor);
 
@@ -251,12 +247,8 @@ impl<T: Parameter> Deref for Param<T> {
                 .write()
                 .unwrap();
 
-            let state = result.as_ref().expect("Should exist when not initialized");
-            let tensor = state.initialize();
-
-            *result = None;
-
-            tensor
+            let state = result.take().expect("Should exist when not initialized");
+            state.initialize()
         })
     }
 }