From a03968e42e26f931d37128e1829abcfb0f81b94f Mon Sep 17 00:00:00 2001
From: Denes Matetelki <denes.matetelki@gmail.com>
Date: Mon, 10 Oct 2011 10:32:19 +0200
Subject: [PATCH] singleton with std::call_once

---
 include/Singleton_call_once.hpp   | 41 +++++++++++++++++++++++++++++++
 test/CMakeLists.txt               |  2 +-
 test/test_Singelton_call_once.hpp | 35 ++++++++++++++++++++++++++
 3 files changed, 77 insertions(+), 1 deletion(-)
 create mode 100644 include/Singleton_call_once.hpp
 create mode 100644 test/test_Singelton_call_once.hpp

diff --git a/include/Singleton_call_once.hpp b/include/Singleton_call_once.hpp
new file mode 100644
index 0000000..117a913
--- /dev/null
+++ b/include/Singleton_call_once.hpp
@@ -0,0 +1,41 @@
+#ifndef SINGLETON_CALL_ONCE_HPP
+#define SINGLETON_CALL_ONCE_HPP
+
+#include <mutex>
+
+template<typename T>
+class Singleton_call_once
+{
+protected:
+
+    Singleton_call_once() {};
+    virtual ~Singleton_call_once() {};
+
+private:
+
+    Singleton_call_once( const Singleton_call_once& );
+    Singleton_call_once& operator=( const Singleton_call_once& );
+
+public:
+
+    static T* getInstance()
+    {
+      std::call_once(m_flag, &Singleton_call_once::do_init);
+      return m_instance;
+    }
+
+private:
+
+    static void do_init()
+    {
+        m_instance = new T();
+    }
+
+    static T* m_instance;
+    static std::once_flag m_flag;
+};
+
+template<class T> T* Singleton_call_once<T>::m_instance = 0;
+template<class T> std::once_flag Singleton_call_once<T>::m_flag;
+
+#endif // SINGLETON_CALL_ONCE_HPP
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index 297a3f7..541227c 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -16,7 +16,7 @@ if(CXXTEST_FOUND)
   generated_main.cpp
   Fixture.hpp
 
-  test_Multiton.hpp
+  test_Singelton_call_once.hpp
 #    test_Singleton.hpp
 #    test_Singleton_meyers.hpp
 #    test_Singleton_DCLP.hpp
diff --git a/test/test_Singelton_call_once.hpp b/test/test_Singelton_call_once.hpp
new file mode 100644
index 0000000..873530a
--- /dev/null
+++ b/test/test_Singelton_call_once.hpp
@@ -0,0 +1,35 @@
+#include <cxxtest/TestSuite.h>
+
+#define private public // need to reach Singleton's private m_instance
+
+#include "Common.hpp"
+#include "Fixture.hpp"
+#include "Singleton_call_once.hpp"
+
+
+class TestSingletonCallOnceSuite : public CxxTest::TestSuite
+{
+
+private:
+
+  class BasicSingleton : public Singleton_call_once<BasicSingleton>
+  {
+    public:
+      int getSeven()
+      {
+        TRACE;
+        return 7;
+      }
+  };
+
+public:
+
+  void testBasic( void )
+  {
+    TEST_HEADER;
+
+    TS_ASSERT_EQUALS( BasicSingleton::getInstance()->getSeven(), 7 );
+  }
+
+
+};