Singleton Design Pattern

lesson#22 - Singleton design pattern/ourGame/source/app.d

@@ -13,6 +13,7 @@ void main() {
         // process events
 
         // update
+		// calling the dummy function
 		GStateManager.getInstance().hello_world();
 
         // render

lesson#22 - Singleton design pattern/ourGame/source/data.d

@@ -1,7 +1,9 @@
 module data;
 
+// mostly used libraries
 public import raylib;
 public import std.stdio: writeln, write;
 
+// window dimensions
 immutable windowWidth = 720;
 immutable windowHeight = 640;

lesson#22 - Singleton design pattern/ourGame/source/gstatemanager.d

@@ -1,10 +1,13 @@
 import data;
 
 class GStateManager {
+    // private class instance
     private static GStateManager instance;
 
+    // private constructor
     private this() { }
 
+    // return the instance; create the instance, if it wasn't created yet
     static GStateManager getInstance() {
         if(instance is null) {
             instance = new GStateManager();
@@ -13,6 +16,7 @@ class GStateManager {
         return instance;
     }
 
+    // dummy function for testing purposes
     void hello_world() {
         writeln("Hello World!");
     }