Another update from ingydotnet^djgoku

Task/Singleton/C++/singleton-3.cpp

@@ -0,0 +1,36 @@
+class Singleton
+{
+public:
+    static Singleton & Instance()
+    {
+        // Since it's a static variable, if the class has already been created,
+        // It won't be created again.
+        // And it **is** thread-safe in C++11.
+
+        static Singleton myInstance;
+
+        // Return a reference to our instance.
+        return myInstance;
+    }
+
+    // delete copy and move constructors and assign operators
+    Singleton(Singleton const&) = delete;             // Copy construct
+    Singleton(Singleton&&) = delete;                  // Move construct
+    Singleton& operator=(Singleton const&) = delete;  // Copy assign
+    Singleton& operator=(Singleton &&) = delete;      // Move assign
+
+    // Any other public methods
+
+protected:
+    Singleton()
+    {
+         // Constructor code goes here.
+    }
+
+    ~Singleton()
+    {
+         // Destructor code goes here.
+    }
+
+     // And any other protected methods.
+}

Task/Singleton/Eiffel/singleton-1.e

@@ -0,0 +1,7 @@
+class
+	SINGLETON
+create {SINGLETON_ACCESS}
+	default_create
+feature
+	-- singleton features go here
+end

Task/Singleton/Eiffel/singleton-2.e

@@ -0,0 +1,10 @@
+frozen class
+	SINGLETON_ACCESS
+feature
+	singleton: SINGLETON
+		once ("PROCESS")
+			create Result
+		ensure
+			Result /= Void
+		end
+end

Task/Singleton/Eiffel/singleton-3.e

@@ -0,0 +1,3 @@
+s: SINGLETON -- declaration somewhere
+
+s := (create{SINGLETON_ACCESS}).singleton -- in some routine

Task/Singleton/Forth/singleton.fth

@@ -0,0 +1,27 @@
+include FMS-SI.f
+
+\ A singleton is created by using normal Forth data
+\ allocation words such as value or variable as instance variables.
+\ Any number of instances of a singleton class may be
+\ instantiated but they will all operate on the same shared data.
+\ The data name space will remain private to objects of the class.
+
+:class singleton
+  0 value a
+  0 value b
+  :m printa a . ;m
+  :m printb b . ;m
+  :m add-a ( n -- ) a + to a ;m
+  :m add-b ( n -- ) b + to b ;m
+;class
+
+singleton s1
+singleton s2
+singleton s3
+
+4 s1 add-a
+9 s2 add-b
+s3 printa \ => 4
+s3 printb \ => 9
+s1 printb \ => 9
+s2 printa \ => 4