Make WeakRef useable with the Properties derive macro

Author: RealKC

glib-macros/tests/properties.rs

@@ -147,6 +147,8 @@ mod foo {
             cell: Cell<u8>,
             #[property(get = Self::overridden, override_class = Base)]
             overridden: PhantomData<u32>,
+            #[property(get, set)]
+            weak_ref_prop: glib::WeakRef<glib::Object>,
         }
 
         impl ObjectImpl for Foo {

glib/src/property.rs

@@ -10,6 +10,9 @@ use std::sync::Mutex;
 use std::sync::RwLock;
 
 use crate::HasParamSpec;
+use crate::IsA;
+use crate::Object;
+use crate::WeakRef;
 
 // rustdoc-stripper-ignore-next
 /// A type that can be used as a property. It covers every type which have an associated `ParamSpec`
@@ -50,6 +53,9 @@ impl<T: Property> Property for Rc<T> {
 impl<T: Property> Property for Arc<T> {
     type Value = T::Value;
 }
+impl<T: IsA<Object> + HasParamSpec> Property for WeakRef<T> {
+    type Value = Option<T>;
+}
 
 // rustdoc-stripper-ignore-next
 /// A container type implementing this trait can be read by the default getter generated by the `Props` macro.
@@ -169,6 +175,21 @@ impl<T> PropertySet for once_cell::unsync::OnceCell<T> {
     }
 }
 
+impl<T: IsA<Object>> PropertyGet for WeakRef<T> {
+    type Value = Option<T>;
+
+    fn get<R, F: Fn(&Self::Value) -> R>(&self, f: F) -> R {
+        f(&self.upgrade())
+    }
+}
+impl<T: IsA<Object>> PropertySet for WeakRef<T> {
+    type SetValue = Option<T>;
+
+    fn set(&self, v: Self::SetValue) {
+        self.set(v.as_ref())
+    }
+}
+
 // Smart pointers wrapping a `PropertyRead`/`PropertyWrite`
 impl<T: PropertyGet> PropertyGet for Rc<T> {
     type Value = T::Value;