Playing with Default behavior for catch-all blocks

src/plugin/Exception.h

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2015 Eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
 /** \file Exception.h -- Default behavior for catch-all exception handlers.
  */
 
 template<typename SubHandlers>
 struct CatchAllVoid
 {
-  template<typename T>
-  static void Handler(T t = T())
+  template<typename UserData>
+  static void Handler(UserData userData)
   {
     try
     {
       std::rethrow_exception(std::current_exception());
     }
-    catch (std::system_error& ex)
+    catch (const std::system_error& ex)
     {
-      SubHandlers::SystemError(ex, t);
+      SubHandlers::Exception(ex, userData);
     }
-    catch (std::runtime_error& ex)
+    catch (const std::runtime_error& ex)
     {
-      SubHandlers::RuntimeError(ex, t);
+      SubHandlers::Exception(ex, userData);
     }
-    catch (std::logic_error& ex)
+    catch (const std::logic_error& ex)
     {
-      SubHandlers::LogicError(ex, t);
+      SubHandlers::Exception(ex, userData);
     }
-    catch (std::exception& ex)
+    catch (const std::exception& ex)
     {
-      SubHandlers::Exception(ex, t);
+      SubHandlers::Exception(ex, userData);
     }
     catch (...)
     {
-      SubHandlers::Unknown(t);
+      SubHandlers::Unknown(userData);
     }
   }
 };
 
 template<typename SubHandlers, typename ReturnType = typename SubHandlers::ReturnType>
 struct CatchAllReturn
 {
-  template<typename T>
-  static ReturnType Handler(T t = T())
+  template<typename UserData>
+  static ReturnType Handler(UserData userData)
   {
     try
     {
       std::rethrow_exception(std::current_exception());
       // Apparently VS 2012 does not realize that this function always throws.
       // Unless we have an explicit return statement, we get a spurious warning C4715 "not all control paths return a value".
       return ReturnType();
     }
-    catch (std::system_error& ex)
+    catch (const std::system_error& ex)
     {
-      return SubHandlers::SystemError(ex, t);
+      return SubHandlers::Exception(ex, userData);
     }
-    catch (std::runtime_error& ex)
+    catch (const std::runtime_error& ex)
     {
-      return SubHandlers::RuntimeError(ex, t);
+      return SubHandlers::Exception(ex, userData);
     }
-    catch (std::logic_error& ex)
+    catch (const std::logic_error& ex)
     {
-      return SubHandlers::LogicError(ex, t);
+      return SubHandlers::Exception(ex, userData);
     }
-    catch (std::exception& ex)
+    catch (const std::exception& ex)
     {
-      return SubHandlers::Exception(ex, t);
+      return SubHandlers::Exception(ex, userData);
     }
     catch (...)
     {
-      return SubHandlers::Unknown(t);
+      return SubHandlers::Unknown(userData);
     }
   }
 };