Re-implement value getter in a nicer way.

	     * include/dynamic-graph/value.h,
	     * src/command/value.cpp.

include/dynamic-graph/value.h

@@ -26,6 +26,17 @@
 
 namespace dynamicgraph {
   namespace command {
+    class Value;
+    class AnyType {
+    public:
+      AnyType(const Value& value);
+      operator int () const;
+      operator double () const;
+      operator std::string () const;
+    private:
+      const Value& value_;
+    };
+
     class DYNAMICGRAPH_EXPORT Value {
     public:
       enum Type {
@@ -36,8 +47,9 @@ namespace dynamicgraph {
 	NB_TYPES
       };
       ~Value();
-      /// template constructor
-      template <class T> Value(const T& value);
+      Value(const int& value);
+      Value(const double& value);
+      Value(const std::string& value);
       /// Copy constructor
       Value(const Value& value);
       // Construct an empty value (None)
@@ -45,46 +57,23 @@ namespace dynamicgraph {
       /// Return the type of the value
       Type type() const;
 
-      /// Return the value if it is a double and throw otherwise
-      double doubleValue () const;
-      /// Return the value if it is a int and throw otherwise
-      int intValue () const;
-      /// Return the value if it is a string and throw otherwise
-      std::string stringValue () const;
+      /// Return the value as a castable value into the approriate type
+      /// double x = value();
+      const AnyType value () const;
       /// Return the name of the type
       static std::string typeName(Type type);
 
       /// Output in a stream
       friend std::ostream& operator<<(std::ostream& os, const Value& value);
     private:
+      friend class AnyType;
+      const double doubleValue() const;
+      const int intValue() const;
+      const std::string stringValue() const;
       Type type_;
       const void* value_;
     };
-
-    // Template constructors
-    template <> inline Value::Value(const int& value)
-    {
-      std::cout << "Constructor of int value" << std::endl;
-      value_ = new int(value);
-      type_ = INT;
-    }
-    template <> inline Value::Value(const double& value)
-    {
-      std::cout << "Constructor of double value" << std::endl;
-      value_ = new double(value);
-      type_ = DOUBLE;
-    }
-    template <> inline Value::Value(const std::string& value)
-    {
-      std::cout << "Constructor of string value" << std::endl;
-      value_ = new std::string(value);
-      type_ = STRING;
-    }
-    template <class T> Value::Value(const T& value)
-    {
-      assert(false);
-    }
-  } // namespace command
+} // namespace command
 } //namespace dynamicgraph
 
 #endif //DYNAMIC_GRAPH_VALUE_H

src/command/value.cpp

@@ -21,6 +21,22 @@
 namespace dynamicgraph {
   namespace command {
 
+    AnyType::AnyType(const Value& value) : value_(value)
+    {
+    }
+    AnyType::operator int () const
+    {
+      return value_.intValue();
+    }
+    AnyType::operator double () const
+    {
+      return value_.doubleValue();
+    }
+    AnyType::operator std::string () const
+    {
+      return value_.stringValue();
+    }
+
     Value::~Value()
     {
       switch(type_) {
@@ -36,6 +52,26 @@ namespace dynamicgraph {
       }
     }
 
+    Value::Value(const int& value)
+    {
+      std::cout << "Constructor of int value" << std::endl;
+      value_ = new int(value);
+      type_ = INT;
+    }
+    Value::Value(const double& value)
+    {
+      std::cout << "Constructor of double value" << std::endl;
+      value_ = new double(value);
+      type_ = DOUBLE;
+    }
+    Value::Value(const std::string& value)
+    {
+      std::cout << "Constructor of string value" << std::endl;
+      value_ = new std::string(value);
+      type_ = STRING;
+    }
+
+
     Value::Value(const Value& value) : type_(value.type_)
     {
       switch(value.type_) {
@@ -59,12 +95,17 @@ namespace dynamicgraph {
       std::cout << "Value empty constructor" << std::endl;
     }
 
+    const AnyType Value::value() const
+    {
+      return AnyType(*this);
+    }
+
     Value::Type Value::type() const
     {
       return type_;
     }
 
-    double Value::doubleValue () const
+    const double Value::doubleValue () const
     {
       double result;
       if (type_ == DOUBLE)
@@ -75,7 +116,7 @@ namespace dynamicgraph {
 			      "value is not a double");
     }
 
-    int Value::intValue () const
+    const int Value::intValue () const
     {
       if (type_ == INT)
 	return *((int*)value_);
@@ -83,7 +124,7 @@ namespace dynamicgraph {
 			      "value is not an int");
     }
 
-    std::string Value::stringValue () const
+    const std::string Value::stringValue () const
     {
       if (type_ == STRING)
 	return *((std::string*)value_);