Data update

Task/Singleton/Ada/singleton-1.adb

@@ -0,0 +1,10 @@
+package Global_Singleton is
+   procedure Set_Data (Value : Integer);
+   function Get_Data return Integer;
+private
+   type Instance_Type is record
+      -- Define instance data elements
+      Data : Integer := 0;
+   end record;
+   Instance : Instance_Type;
+end Global_Singleton;

Task/Singleton/Ada/singleton-2.adb

@@ -0,0 +1,21 @@
+package body Global_Singleton is
+
+   --------------
+   -- Set_Data --
+   --------------
+
+   procedure Set_Data (Value : Integer) is
+   begin
+      Instance.Data := Value;
+   end Set_Data;
+
+   --------------
+   -- Get_Data --
+   --------------
+
+   function Get_Data return Integer is
+   begin
+      return Instance.Data;
+   end Get_Data;
+
+end Global_Singleton;

Task/Singleton/Ada/singleton-3.adb

@@ -0,0 +1,11 @@
+package Protected_Singleton is
+   procedure Set_Data (Value : Integer);
+   function Get_Data return Integer;
+private
+   protected Instance is
+      procedure Set(Value : Integer);
+      function Get return Integer;
+   private
+      Data : Integer := 0;
+   end Instance_Type;
+end Protected_Singleton;

Task/Singleton/Ada/singleton-4.adb

@@ -0,0 +1,47 @@
+package body Protected_Singleton is
+
+   --------------
+   -- Set_Data --
+   --------------
+
+   procedure Set_Data (Value : Integer) is
+   begin
+      Instance.Set(Value);
+   end Set_Data;
+
+   --------------
+   -- Get_Data --
+   --------------
+
+   function Get_Data return Integer is
+   begin
+      return Instance.Get;
+   end Get_Data;
+
+   --------------
+   -- Instance --
+   --------------
+
+   protected body Instance is
+
+      ---------
+      -- Set --
+      ---------
+
+      procedure Set (Value : Integer) is
+      begin
+         Data := Value;
+      end Set;
+
+      ---------
+      -- Get --
+      ---------
+
+      function Get return Integer is
+      begin
+         return Data;
+      end Get;
+
+   end Instance;
+
+end Protected_Singleton;

Task/Singleton/EMal/singleton.emal

@@ -1,17 +1,17 @@
 type Singleton
 model
   text greeting
-  fun speak = void by block do writeLine(me.greeting + " I'm a singleton") end
+  fun speak ← void by block do writeLine(me.greeting + " I'm a singleton") end
 end
 Singleton instance
-fun getInstance = Singleton by block
-  if instance == null do instance = Singleton() end
+fun getInstance ← Singleton by block
+  if instance æ null do instance ← Singleton() end
   return instance
 end
 type SomeOtherType
-Singleton s1 = Singleton.getInstance()
-s1.greeting = "Hello"
-Singleton s2 = Singleton.getInstance()
+Singleton s1 ← Singleton.getInstance()
+s1.greeting ← "Hello"
+Singleton s2 ← Singleton.getInstance()
 s2.greeting.append(", World!")
-writeLine(s1 + " and " + s2 + " are the same object: " + (s1 == s2) + ", s2: " + s2.greeting)
+writeLine(s1 + " and " + s2 + " are the same object: " + (s1 æ s2) + ", s2: " + s2.greeting)
 s1.speak() # call instance method

Task/Singleton/Pluto/singleton-1.pluto

@@ -0,0 +1,19 @@
+-- Singleton.pluto --
+
+local instance = nil
+
+class singleton
+    static function getInstance()
+        if !instance then new singleton() end
+        return instance
+    end
+
+    function __construct()
+        assert(!instance, "The singleton instance already exists.")
+        instance = self
+    end
+
+    function print()
+        print("Hello, I'm a singleton.")
+    end
+end

Task/Singleton/Pluto/singleton-2.pluto

@@ -0,0 +1,12 @@
+-- Singleton_user.pluto --
+
+require "Singleton"
+
+local s = singleton.getInstance()
+s:print()
+local t = singleton.getInstance()
+t:print()
+print(s == t)              -- true, as same object
+print(instance)            -- nil
+local u = new singleton()  -- throws an error
+u:print()                  -- not executed