Fix and compactify QNotifiedProperty

The static observer can live in a union with the inline observers. We
only need to take care of calling the ctors and dtors manually then.

In order for any observers to be called in the presence of a static
observer, the static observer has to be called after the other
observers.

Change-Id: I2f56fa64f3fe6fcd7f06cc403929362da7d86f65
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 32 insertions, 0 deletions

diff --git a/src/corelib/kernel/qproperty.h b/src/corelib/kernel/qproperty.h
index e2a6172d84..f0156fac02 100644
--- a/src/corelib/kernel/qproperty.h
+++ b/src/corelib/kernel/qproperty.h
@@ -590,6 +590,17 @@ public:
     {
         setSource(property);
     }
+
+    template <typename PropertyType, typename Class, void(Class::*Callback)()>
+    QPropertyChangeHandler(const QNotifiedProperty<PropertyType, Callback> &property, Functor handler)
+        : QPropertyObserver([](QPropertyObserver *self, void *) {
+              auto This = static_cast<QPropertyChangeHandler<Functor>*>(self);
+              This->m_handler();
+          })
+        , m_handler(handler)
+    {
+        setSource(property);
+    }
 };
 
 template <typename T>
@@ -613,6 +624,27 @@ QPropertyChangeHandler<Functor> QProperty<T>::subscribe(Functor f)
     return onValueChanged(f);
 }
 
+template <typename T, typename Class, void(Class::*Callback)()>
+template<typename Functor>
+QPropertyChangeHandler<Functor> QNotifiedProperty<T, Callback>::onValueChanged(Functor f)
+{
+#if defined(__cpp_lib_is_invocable) && (__cpp_lib_is_invocable >= 201703L)
+    static_assert(std::is_invocable_v<Functor>, "Functor callback must be callable without any parameters");
+#endif
+    return QPropertyChangeHandler<Functor>(*this, f);
+}
+
+template <typename T, typename Class, void(Class::*Callback)()>
+template<typename Functor>
+QPropertyChangeHandler<Functor> QNotifiedProperty<T, Callback>::subscribe(Functor f)
+{
+#if defined(__cpp_lib_is_invocable) && (__cpp_lib_is_invocable >= 201703L)
+    static_assert(std::is_invocable_v<Functor>, "Functor callback must be callable without any parameters");
+#endif
+    f();
+    return onValueChanged(f);
+}
+
 template <auto propertyMember, auto callbackMember>
 struct QPropertyMemberChangeHandler;