2 files changed, 18 insertions, 2 deletions

diff --git a/src/sptr.h b/src/sptr.h
index 23c21dc..0ea8bca 100644
--- a/src/sptr.h
+++ b/src/sptr.h
@@ -4,9 +4,14 @@
 #include <stdint.h>
 #include <stdio.h>
 
+template<typename T> class SPtr;
+template< typename Tb, typename Ta > SPtr<Tb> SPtrCast( SPtr<Ta> src );
+
 template<typename T>
 class SPtr
 {
+        template<typename Tb, typename Ta>
+        friend SPtr<Tb> SPtrCast( SPtr<Ta> pt );
 public:
         SPtr() :
                 pRefCnt( NULL ),
@@ -96,4 +101,14 @@ private:
         T *pData;
 };
 
+template< typename Tb, typename Ta > SPtr<Tb> SPtrCast( SPtr<Ta> src )
+{
+        SPtr<Tb> ret;
+        ret.pRefCnt = src.pRefCnt;
+        ret.pData = dynamic_cast<Tb *>(src.pData);
+        if( ret.pRefCnt )
+                (*(ret.pRefCnt)) += 1;
+        return ret;
+}
+
 #endif
diff --git a/src/tests/sptr.cpp b/src/tests/sptr.cpp
index bc00f78..252463b 100644
--- a/src/tests/sptr.cpp
+++ b/src/tests/sptr.cpp
@@ -65,11 +65,12 @@ int main()
                         beAnnoying( pt3 );
 
                         {
-                                SPtr<Annoy2> pt4( dynamic_cast<SPtr<Annoy2> >(pt3) );
+                                SPtr<Annoy2> pt4( SPtrCast<Annoy2>( pt3 ) );
                                 printf("Count: %d\n", pt4.count() );
 
-                                pt4.go2();
+                                pt4->go2();
                         }
+                        printf("Count: %d\n", pt.count() );
                 }
                 printf("Count: %d\n", pt.count() );
         }