From 294c254f29317e9ddffbb904ea273a72b29432ac Mon Sep 17 00:00:00 2001
From: Ichthyostega <prg@ichthyostega.de>
Date: Sat, 20 Jun 2009 23:17:22 +0200
Subject: [PATCH] Fix instantiation of Tuple datastructs

---
 src/lib/meta/tuple.hpp               | 27 +++++++++++++++++++++++++++
 src/lib/util.hpp                     | 10 ++++++++++
 src/proc/control/command-closure.hpp | 13 ++++++++++---
 3 files changed, 47 insertions(+), 3 deletions(-)

diff --git a/src/lib/meta/tuple.hpp b/src/lib/meta/tuple.hpp
index ec8f5dd72..4cb0a49d8 100644
--- a/src/lib/meta/tuple.hpp
+++ b/src/lib/meta/tuple.hpp
@@ -294,6 +294,33 @@ namespace typelist{
     };
   
   
+  template<>
+  struct Tuple<Types<> >
+    : Tuple<NullType>
+    {
+      enum  { SIZE = 0 };
+      typedef Tuple<NullType> TupleNull;
+      
+      Tuple ( NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            , NullType =NullType()
+            )
+        { } ///< end recursion of chained ctor calls
+      
+      
+      template<uint> struct ShiftedTuple       { typedef TupleNull Type; };
+      
+      template<uint> TupleNull&  getShifted () { return static_cast<TupleNull&> (*this); }
+      template<uint> NullType&        getAt () { return getHead(); }
+    };
+  
+  
   
   namespace tuple { // some convenience access functions
   
diff --git a/src/lib/util.hpp b/src/lib/util.hpp
index a835fc443..40845283f 100644
--- a/src/lib/util.hpp
+++ b/src/lib/util.hpp
@@ -190,6 +190,16 @@ namespace util {
   }
   
   
+  /** shortcut to save some typing when having to define
+   *  const and non-const variants of member functions
+   */
+  template<class OBJ>
+  OBJ*
+  unConst (const OBJ* o)
+  {
+    return const_cast<OBJ*> (o);
+  }
+  
   
   
   /** produce an identifier based on the given string.
diff --git a/src/proc/control/command-closure.hpp b/src/proc/control/command-closure.hpp
index 56085e74d..56efd3302 100644
--- a/src/proc/control/command-closure.hpp
+++ b/src/proc/control/command-closure.hpp
@@ -41,6 +41,7 @@
 #include "lib/meta/function-closure.hpp"
 #include "lib/meta/function-erasure.hpp"
 #include "lib/meta/tuple.hpp"
+#include "lib/util.hpp"
 
 #include <tr1/memory>
 #include <tr1/functional>
@@ -59,6 +60,7 @@ namespace control {
   
 //  using lumiera::Symbol;
 //  using std::tr1::shared_ptr;
+  using util::unConst;
   using std::string;
   using std::ostream;
   using std::tr1::function;
@@ -110,7 +112,8 @@ namespace control {
   class ParamAccessor
     : public BASE
     {
-      TY& element() { return BASE::template getAt<idx>(); }
+      TY      & element()        { return          BASE::template getAt<idx>(); }
+      TY const& element()  const { return unConst(this)->template getAt<idx>(); }
       
     public:
         
@@ -123,7 +126,7 @@ namespace control {
       string
       dump (string const& prefix = "(")  const
         {
-          return BASE::dump (prefix+element());
+          return BASE::dump (prefix+element()+",");
         }
       
       
@@ -145,7 +148,11 @@ namespace control {
       string
       dump (string const& prefix)  const
         { 
-          return prefix+")";
+          if (1 < prefix.length())
+            // remove trailing comma...
+            return prefix.substr (0, prefix.length()-1) +")";
+          else
+            return prefix+")";
         }
       
     };