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

include/loki/Singleton.h

@@ -71,7 +71,7 @@ namespace Loki
         template <typename T>
         struct Deleter
         {
-			typedef void (*Type)(T*);
+            typedef void (*Type)(T*);
             static void Delete(T* pObj)
             { delete pObj; }
         };
@@ -138,13 +138,13 @@ namespace Loki
         std::atexit(Private::AtExitFn);
     }
 
-	template <typename T>
+    template <typename T>
     void SetLongevity(T* pDynObject, unsigned int longevity,
-		typename Private::Deleter<T>::Type d = Private::Deleter<T>::Delete)
+        typename Private::Deleter<T>::Type d = Private::Deleter<T>::Delete)
     {
-		SetLongevity<T, typename Private::Deleter<T>::Type>(pDynObject, longevity, d);
+        SetLongevity<T, typename Private::Deleter<T>::Type>(pDynObject, longevity, d);
-	}
+    }
-	
+    
 ////////////////////////////////////////////////////////////////////////////////
 // class template CreateUsingNew
 // Implementation of the CreationPolicy used by SingletonHolder
@@ -194,7 +194,7 @@ namespace Loki
 
     template <class T> struct CreateStatic
     {
-    	
+        
 #ifdef _MSC_VER
 #pragma warning( push ) 
 #pragma warning( disable : 4121 )
@@ -283,7 +283,76 @@ namespace Loki
 #ifndef ATEXIT_FIXED
     template <class T> bool PhoenixSingleton<T>::destroyedOnce_ = false;
 #endif
+
+////////////////////////////////////////////////////////////////////////////////
+// class template DeletableSingleton
+// Copyright (c) 2004 by Curtis Krauskopf - curtis@decompile.com
+//
+// A DeletableSingleton allows the instantiated singleton to be 
+// destroyed at any time. The singleton can be reinstantiated at 
+// any time, even during program termination.
+// If the singleton exists when the program terminates, it will 
+// be automatically deleted.
+//
+// The singleton can be deleted manually:
+// DeletableSingleton<MyClass>::GracefulDelete();
+////////////////////////////////////////////////////////////////////////////////
         
+    template <class T>
+    class DeletableSingleton
+    {
+    public:
+
+        static void ScheduleDestruction(T*, atexit_pfn_t pFun)
+        {
+            static bool firstPass = true;
+            isDead = false;
+            deleter = pFun;
+            if (firstPass || needCallback)
+            {
+                std::atexit(atexitCallback);
+                firstPass = false;
+                needCallback = false;
+            }
+        }
+    
+        static void OnDeadReference()
+        { 
+        }
+    
+        static void GracefulDelete()
+        {
+            if (isDead)
+                return;
+            isDead = true;
+            deleter();
+        }
+    
+    protected:
+        static atexit_pfn_t deleter;
+        static bool isDead;
+        static bool needCallback;
+        
+        static void atexitCallback()
+        {
+#ifdef ATEXIT_FIXED
+            needCallback = true;
+#else
+            needCallback = false;
+#endif
+            GracefulDelete();
+        }
+    };
+    
+    template <class T>
+    atexit_pfn_t DeletableSingleton<T>::deleter = 0;
+    
+    template <class T>
+    bool DeletableSingleton<T>::isDead = true;
+    
+    template <class T>
+    bool DeletableSingleton<T>::needCallback = true;
+
 ////////////////////////////////////////////////////////////////////////////////
 // class template Adapter
 // Helper for SingletonWithLongevity below
@@ -435,7 +504,7 @@ namespace Loki
         {
             if (destroyed_)
             {
-            	destroyed_ = false;
+                destroyed_ = false;
                 LifetimePolicy<T>::OnDeadReference();
             }
             pInstance_ = CreationPolicy<T>::Create();

test/Makefile

@@ -8,6 +8,7 @@ SUBTARGETS	= \
 		sub-OrderedStatic \
 		sub-RegressionTest \
 		sub-SafeFormat \
+		sub-Singleton \
 		sub-SmallObj 
 
 all: $(SUBTARGETS)
@@ -32,6 +33,12 @@ sub-SafeFormat: FORCE
 	$(MAKE) -f $(MAKEFILE)
 	@cd ..
 
+sub-Singleton: FORCE
+	cd Singleton && \
+	$(MAKE) -f $(MAKEFILE)-DeletableSingleton && \
+	$(MAKE) -f $(MAKEFILE)-Phoenix 
+	@cd ..
+	
 sub-SmallObj: FORCE
 	cd SmallObj && \
 	$(MAKE) -f $(MAKEFILE)

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;
+}
+

test/Singleton/Makefile-DeletableSingleton

@@ -0,0 +1,32 @@
+
+
+CPP = g++
+CC = gcc
+OBJ = DeletableSingleton.o 
+LINKOBJ = DeletableSingleton.o
+CXXINCS = -I./../../include
+LIBS = -L../../lib -lloki
+CXXFLAGS = $(CXXINCS) -O2 -DNDEBUG
+BIN = DeletableSingleton-gcc.exe
+RM = rm -f
+CHK_DIR_EXISTS= if not exist
+MKDIR = mkdir
+
+.PHONY: all all-before all-after clean clean-custom
+
+all: all-before $(BIN) all-after
+
+
+clean: clean-custom
+	${RM} $(OBJ) $(BIN)
+
+$(BIN): $(OBJ)
+	$(CPP) $(LINKOBJ) -o DeletableSingleton-gcc.exe $(LIBS)
+
+check_tmp: 
+	@$(CHK_DIR_EXISTS) "" $(MKDIR) "tmp"
+	
+Factory.o: Factory.cpp
+	$(CPP) -c DeletableSingleton.cpp -o DeletableSingleton.o $(CXXFLAGS)
+
+

test/Singleton/Makefile-Phoenix

@@ -0,0 +1,32 @@
+
+
+CPP = g++
+CC = gcc
+OBJ = Phoenix.o 
+LINKOBJ = Phoenix.o
+CXXINCS = -I./../../include
+LIBS = -L../../lib -lloki
+CXXFLAGS = $(CXXINCS) -O2 -DNDEBUG
+BIN = Phoenix-gcc.exe
+RM = rm -f
+CHK_DIR_EXISTS= if not exist
+MKDIR = mkdir
+
+.PHONY: all all-before all-after clean clean-custom
+
+all: all-before $(BIN) all-after
+
+
+clean: clean-custom
+	${RM} $(OBJ) $(BIN)
+
+$(BIN): $(OBJ)
+	$(CPP) $(LINKOBJ) -o Phoenix-gcc.exe $(LIBS)
+
+check_tmp: 
+	@$(CHK_DIR_EXISTS) "" $(MKDIR) "tmp"
+	
+Factory.o: Factory.cpp
+	$(CPP) -c Phoenix.cpp -o Phoenix.o $(CXXFLAGS)
+
+

test/Singleton/Phoenix.cpp

@@ -0,0 +1,91 @@
+////////////////////////////////////////////////////////////////////////////////
+// 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.
+////////////////////////////////////////////////////////////////////////////////
+
+// A singleton Log object that resurrects itself after
+// it has been automatically destroyed during program
+// termination.  When a dead-reference to the Log
+// singleton is detected, it is resurrected automatically.
+//
+// Expected output:
+//   Example c'tor
+//   Log c'tor
+//   Log now instantiated.
+//   Log d'tor
+//   Example d'tor starting
+//   Log c'tor
+//   Log: inside Example d'tor
+//   Example d'tor finished
+//
+// The last line of the output only appears when this
+// program is compiled with the ATEXIT_FIXED symbol
+// defined (see the Loki library and the CUJ article).
+//
+
+#include <iostream>
+#include "loki/Singleton.h"   // for Loki::SingletonHolder
+
+using namespace std;   // okay for small programs
+using namespace Loki;  // okay for small programs
+
+class Log
+{
+public:
+    Log()
+    {
+        echo("Log c'tor");
+    }
+    ~Log()
+    {
+        echo("Log d'tor");
+    }
+    void echo(const char *s)
+    {
+        cout << s << endl;
+    }
+};
+
+typedef SingletonHolder<Log, CreateUsingNew, PhoenixSingleton> log;
+
+
+// A generic example class that stores and echoes a const char.
+//
+class Example
+{
+public:
+    Example()
+    {
+        echo("Example c'tor");
+    }
+    ~Example()
+    {
+        echo("Example d'tor starting");
+        log::Instance().echo("Log: inside Example d'tor");
+        echo("Example d'tor finished");
+    }
+    void echo(const char *s)
+    {
+        cout << s << endl;
+    }
+};
+
+
+int main(int argc, char* argv[])
+{
+    Example *example = new Example();
+     SetLongevity<Example, void (*)(Example*)>(example, 1, &Loki::Private::Deleter<Example>::Delete);
+    log::Instance().echo("Log now instantiated.");
+    
+#if defined(__BORLANDC__) || defined(__GNUC__) || defined(_MSC_VER)
+    system("pause"); // Stop console window from closing if run from IDE.
+#endif
+
+    return 0;
+}
+

test/Singleton/make.msvc.bat

@@ -0,0 +1,31 @@
+if not exist tmp\ mkdir tmp
+
+
+::  DeletableSingleton.cpp
+
+cl -c -Zm200 -O2 -DNDEBUG -MT -EHsc -GR -W0 -wd4710 -I"." -I"..\..\include" -Fotmp\ DeletableSingleton.cpp
+
+if not defined LOKI_MSVC_NOLIB (
+
+link /NOLOGO /SUBSYSTEM:CONSOLE /incremental:no /OUT:"DeletableSingleton-msvc.exe" ..\..\lib\loki.lib tmp\DeletableSingleton.obj 
+
+) else (
+
+link /NOLOGO /SUBSYSTEM:CONSOLE /incremental:no /OUT:"DeletableSingleton-msvc.exe" tmp\DeletableSingleton.obj ..\..\lib\SmallObj.obj ..\..\lib\Singleton.obj 
+
+)
+
+
+::  Phoenix.cpp
+
+cl -c -Zm200 -O2 -DNDEBUG -MT -EHsc -GR -W0 -wd4710 -I"." -I"..\..\include" -Fotmp\ Phoenix.cpp
+
+if not defined LOKI_MSVC_NOLIB (
+
+link /NOLOGO /SUBSYSTEM:CONSOLE /incremental:no /OUT:"Phoenix-msvc.exe" ..\..\lib\loki.lib tmp\Phoenix.obj 
+
+) else (
+
+link /NOLOGO /SUBSYSTEM:CONSOLE /incremental:no /OUT:"Phoenix-msvc.exe" tmp\Phoenix.obj ..\..\lib\SmallObj.obj ..\..\lib\Singleton.obj 
+
+)

test/make.msvc.bat

@@ -23,6 +23,10 @@ cd SafeFormat
 call make.msvc.bat
 cd ..
 
+cd Singleton
+call make.msvc.bat
+cd ..
+
 cd SmallObj
 call make.msvc.bat
 cd ..