adding scoped_exit helper

include/fc/scoped_exit.hpp

@@ -0,0 +1,32 @@
+#pragma once
+
+namespace fc {
+
+   template<typename Callback>
+   class scoped_exit {
+      public:
+         template<typename C>
+         scoped_exit( C&& c ):callback( std::forward<C>(c) ){}
+         scoped_exit( scoped_exit&& mv ):callback( std::move( mv.callback ) ){}
+
+         ~scoped_exit() {
+            try { callback(); } catch( ... ) {}
+         }
+
+         scoped_exit& operator = ( scoped_exit&& mv ) {
+            callback = std::move(mv);
+            return *this;
+         }
+      private:
+         scoped_exit( const scoped_exit& );
+         scoped_exit& operator=( const scoped_exit& );
+
+         Callback callback;
+   };
+
+   template<typename Callback>
+   scoped_exit<Callback> make_scoped_exit( Callback&& c ) {
+      return scoped_exit<Callback>( std::forward<Callback>(c) );
+   }
+
+}