introduce value property

nicegui/elements/value_element.py

@@ -17,16 +17,26 @@ class ValueElement(Element):
         super().__init__(view)
 
         self.change_handler = on_change
-        self.value = value
+        self.value_ = value
         self.bind_value_to(self.view, 'value', forward=self.value_to_view)
 
+    @property
+    def value(self):
+        return self.value_
+
+    @value.setter
+    def value(self, value: Any):
+        change = self.value_ != value
+        self.value_ = value
+        if change:
+            arguments = ValueChangeEventArguments(sender=self, value=self.value)
+            handle_event(self.change_handler, arguments, update=self.parent_view)
+
     def value_to_view(self, value):
         return value
 
     def handle_change(self, msg):
         self.value = msg['value']
-        arguments = ValueChangeEventArguments(sender=self, value=self.value)
-        handle_event(self.change_handler, arguments, update=self.parent_view)
 
     def bind_value_to(self, target_object, target_name, *, forward=lambda x: x):
         bind_to(self, 'value', target_object, target_name, forward=forward)