Merge branch 'GaudiFunctional-RangeZipSizeCheckImprovedErrorMessage' into 'master'

Gaudi functional range zip - size check improved error message

See merge request !297

GaudiAlg/GaudiAlg/FunctionalDetails.h

@@ -24,6 +24,21 @@ namespace Gaudi { namespace Functional { namespace details {
     namespace zip
     {
 
+      /// Print the parameter
+      template <typename OS, typename Arg>
+      void printSizes(OS& out, Arg&& arg)
+      {
+        out << "SizeOf'" << System::typeinfoName(typeid(Arg)) 
+            << "'=" << std::forward<Arg>(arg).size();
+      }
+
+      /// Print the parameters
+      template <typename OS, typename Arg, typename... Args>
+      void printSizes(OS& out, Arg&& arg, Args&&... args)
+      {
+        printSizes(out,arg); out << ", "; printSizes(out,args...);
+      }
+
       /// Resolve case there is only one container in the range
       template < typename A >
       inline bool check_sizes( const A& ) noexcept { return true; }
@@ -47,9 +62,14 @@ namespace Gaudi { namespace Functional { namespace details {
       inline decltype(auto) verifySizes( Args&... args )
       {
         if ( UNLIKELY( !check_sizes( args... ) ) )
-        { throw GaudiException( "Zipped containers have different sizes.",
+        { 
+          std::ostringstream mess;
+          mess << "Zipped containers have different sizes : ";
+          printSizes(mess,args...);
+          throw GaudiException( mess.str(),
                                 "Gaudi::Functional::details::zip::verifySizes",
-                                StatusCode::FAILURE ); }
+                                StatusCode::FAILURE ); 
+        }
       }
 
       /// Zips multiple containers together to form a single range