diff -r e41c2907fb49 -r 3c176c65d33b src/lemon/maps.h
--- a/src/lemon/maps.h	Thu Feb 24 17:48:25 2005 +0000
+++ b/src/lemon/maps.h	Fri Feb 25 14:50:22 2005 +0000
@@ -186,6 +186,49 @@
     };
   };
 
+  ///Convert the \c Value of a maps to another type.
+
+  ///This \ref concept::ReadMap "read only map"
+  ///converts the \c Value of a maps to type \c T.
+  ///Its \c Value is inherited from \c M.
+  ///
+  ///Actually,
+  ///\code
+  ///  ConvertMap<X> sh(x,v);
+  ///\endcode
+  ///it is equivalent with
+  ///\code
+  ///  ConstMap<X::Key, X::Value> c_tmp(v);
+  ///  AddMap<X, ConstMap<X::Key, X::Value> > sh(x,v);
+  ///\endcode
+  ///\bug wrong documentation
+  template<class M, class T> 
+  class ConvertMap
+  {
+    const M &m;
+  public:
+    typedef typename M::Key Key;
+    typedef T Value;
+
+    ///Constructor
+
+    ///Constructor
+    ///\param _m is the undelying map
+    ///\param _v is the convert value
+    ConvertMap(const M &_m) : m(_m) {};
+    Value operator[](Key k) const {return m[k];}
+  };
+  
+  ///Returns an \ref ConvertMap class
+
+  ///This function just returns an \ref ConvertMap class.
+  ///\relates ConvertMap
+  ///\todo The order of the template parameters are changed.
+  template<class T, class M>
+  inline ConvertMap<M,T> convertMap(const M &m) 
+  {
+    return ConvertMap<M,T>(m);
+  }
 
   ///Sum of two maps