Added teardown styled use effect

src/dawn/state/StateProperty.hpp

@@ -10,6 +10,8 @@ namespace Dawn {
   class IStateProperty {
     public:
       std::vector<std::function<void()>> _effectListners;
+      std::vector<std::function<std::function<void()>()>> _effectListnersWithTeardown;
+      std::vector<std::function<void()>> _effectTeardowns;
   };
 
   template<class V>
@@ -26,12 +28,28 @@ namespace Dawn {
         this->previous = this->_realValue;
         this->_realValue = val;
 
+        // Run the teardowns
+        auto itTeardown = this->_effectTeardowns.begin();
+        while(itTeardown != this->_effectTeardowns.end()) {
+          (*itTeardown)();
+          ++itTeardown;
+        }
+        this->_effectTeardowns.clear();
+
         // Notify the effect listeners
         auto itEffect = this->_effectListners.begin();
         while(itEffect != this->_effectListners.end()) {
           (*itEffect)();
           ++itEffect;
         }
+
+        // Notify the teardown effect listeners
+        auto itWithTeardown = this->_effectListnersWithTeardown.begin();
+        while(itWithTeardown != this->_effectListnersWithTeardown.end()) {
+          auto teardown = (*itWithTeardown)();
+          this->_effectTeardowns.push_back(teardown);
+          ++itWithTeardown;
+        }
       }
 
     public: