Added osg::MakeString class to make it easier to create std::string's using std::ostream style << usage.

include/osg/io_utils

@@ -16,6 +16,7 @@
 
 #include <ostream>
 #include <istream>
+#include <sstream>
 
 #include <osg/Vec4d>
 #include <osg/Vec4ub>
@@ -35,6 +36,43 @@
 namespace osg {
 
 
+/** Convinience class for building std::string using stringstream.
+  * Usage:
+  *    MakeString str;
+  *    std::string s = str<<"Mix strings with numbers "<<0" ;
+  *    std::string s2 = str.clear()<<"and other classes such as ("<<osg::Vec3(0.0,1.0,3.0)<<)" ; */
+class MakeString
+{
+    public:
+        MakeString() {}
+
+        std::stringstream sstream;
+
+        template<typename T>
+        MakeString& operator << (const T& t)
+        {
+            sstream << t;
+            return *this;
+        }
+
+        MakeString& operator << (std::ostream& (*fun)(std::ostream&))
+        {
+            sstream << fun;
+            return *this;
+        }
+
+        inline MakeString& clear() { sstream.str("") ; return *this; }
+
+        inline operator std::string () const { return sstream.str(); }
+
+        inline std::string str() const { return sstream.str(); }
+        inline const char* c_str() const { return sstream.str().c_str(); }
+};
+
+
+
+inline std::ostream& operator << (std::ostream& output, const MakeString& str) { output << str.str(); return output; }
+
 //////////////////////////////////////////////////////////////////////////
 // Vec2f streaming operators
 inline std::ostream& operator << (std::ostream& output, const Vec2f& vec)