add DeletableSingleton policy and examples from Curtis Krauskopf's CUJ article 'Creating Dynamic Singletons & the Loki Library' - www.decompile.com

git-svn-id: svn://svn.code.sf.net/p/loki-lib/code/trunk@307 7ec92016-0320-0410-acc4-a06ded1c099a

test/Singleton/DeletableSingleton.cpp

@@ -0,0 +1,80 @@
+////////////////////////////////////////////////////////////////////////////////
+// The Loki Library
+// Copyright (c) 2005 by Curtis Krauskopf
+// Copyright (c) 2005 by Peter Kuemmel
+//
+// Code covered by the MIT License
+// The authors make no representations about the suitability of this software
+// for any purpose. It is provided "as is" without express or implied warranty.
+////////////////////////////////////////////////////////////////////////////////
+
+// Show an example of a Loki policy that uses DeletableSingleton.
+//
+// Expected output:
+//
+//    Log::Log()
+//    Log singleton instantiated
+//    Going to manually delete log.
+//    Log::~Log()
+//    Log::Log()
+//    Log reinstantiated.
+//    Going to terminate program now.
+//    Log::~Log()
+//
+
+#include <iostream>
+#include "loki/Singleton.h"   // for Loki::SingletonHolder
+
+using namespace std;   // okay for small programs
+using namespace Loki;  // okay for small programs
+
+// A singleton Log object derived from the Example class.
+// Its longevity is set by the user on the command line.
+//
+class Log
+{
+public:
+    Log()
+    {
+        print("Log::Log()");
+    };
+    ~Log()
+    {
+        print("Log::~Log()");
+    }
+    void print(const char *s)
+    {
+        cout << s << endl;
+    }
+};
+
+typedef SingletonHolder<Log, CreateUsingNew, DeletableSingleton> log;
+
+class Example
+{
+public:
+    void method()
+    {
+        cout << "test\n";
+    }
+};
+
+
+int main(int argc, char *argv[])
+{
+    // Instantiate both singletons by calling them...
+    log::Instance().print("Log singleton instantiated");
+    log::Instance().print("Going to manually delete log.");
+
+    DeletableSingleton<Log>::GracefulDelete();
+
+    log::Instance().print("Log reinstantiated.");
+    log::Instance().print("Going to terminate program now.");
+
+#if defined(__BORLANDC__) || defined(__GNUC__) || defined(_MSC_VER)
+    system("pause"); // Stop console window from closing if run from IDE.
+#endif
+
+    return 0;
+}
+