observer design pattern

lesson#24 - Observer Design Pattern/ObserverDesignPattern/main.d

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+import std.stdio: writeln;
+
+interface IObserver {
+	void update(string msg);
+}
+
+class WhatsApp {
+	private IObserver[] list;
+
+	this() {}
+	~this() {}
+
+	void addClient(IObserver o) {
+		list ~= o;
+	}
+
+	void removeClient(IObserver o) {
+		import std.algorithm: remove;
+		list = list.remove!(a => a is o);
+	}
+
+	void notify(string msg) {
+		foreach(client; list) {
+			client.update(msg);
+		}
+	}
+}
+
+class Person: IObserver {
+	string name;
+
+	this(string name) {
+		this.name = name;
+	}
+
+	void update(string msg) {
+		writeln(name, "\t: notified. [", msg, "]");
+	}
+}
+
+void main() {
+	WhatsApp app = new WhatsApp();
+
+	Person anna = new Person("Anna");
+	Person john = new Person("John");
+	Person markus = new Person("Markus");
+
+	app.addClient(anna);
+	app.addClient(john);
+	app.addClient(markus);
+
+	app.notify("hello, world!");
+
+	app.removeClient(john);
+
+	app.notify("john left the conversation");
+}
+
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lesson#24 - Observer Design Pattern/ourGame/.gitignore

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+.dub
+docs.json
+__dummy.html
+docs/
+/ourgame
+ourgame.so
+ourgame.dylib
+ourgame.dll
+ourgame.a
+ourgame.lib
+ourgame-test-*
+*.exe
+*.o
+*.obj
+*.lst

lesson#24 - Observer Design Pattern/ourGame/dub.json

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+{
+	"authors": [
+		"rillk500"
+	],
+	"copyright": "no copyright",
+	"dependencies": {
+		"raylib-d": "~>3.0.3"
+	},
+	"description": "2D game",
+	"libs": [
+		"raylib"
+	],
+	"license": "no license",
+	"name": "ourgame"
+}

lesson#24 - Observer Design Pattern/ourGame/dub.selections.json

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+{
+	"fileVersion": 1,
+	"versions": {
+		"ddmp": "0.0.1-0.dev.3",
+		"fluent-asserts": "0.13.3",
+		"libdparse": "0.14.0",
+		"raylib-d": "3.0.3",
+		"stdx-allocator": "2.77.5"
+	}
+}

lesson#24 - Observer Design Pattern/ourGame/source/app.d

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+import data;
+import gstatemanager;
+
+import menu;
+import play;
+
+void main() {
+	/*// init
+    InitWindow(windowWidth, windowHeight, "Mission X");
+    scope(exit) CloseWindow();
+
+	// set frames per second
+    SetTargetFPS(60);
+
+    while(!WindowShouldClose()) {
+        // process events
+
+        // update
+		// calling the dummy function
+		GStateManager.getInstance().hello_world();
+
+        // render
+        BeginDrawing();
+		scope(exit) EndDrawing();
+
+        ClearBackground(Colors.WHITE);
+		// .. draw ..
+    }*/
+}
+
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lesson#24 - Observer Design Pattern/ourGame/source/data.d

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+module data;
+
+// mostly used libraries
+public import raylib;
+public import std.stdio: writeln, write;
+
+// window dimensions
+immutable windowWidth = 720;
+immutable windowHeight = 640;
+
+// state interface
+interface IState {
+	void run();
+}
+

lesson#24 - Observer Design Pattern/ourGame/source/gstatemanager.d

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+import data;
+
+class GStateManager {
+    // private class instance
+    private static GStateManager instance;
+    
+    // IState interface
+    private IState state;
+
+    // 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();
+        }
+
+        return instance;
+    }
+
+    // set game state
+    void setState(IState state) {
+        this.state = state;
+    }
+
+    // execute the current game state code
+    void execute() {
+        if(state is null) {
+            return;
+        }
+
+        state.run();
+    }
+}
+
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lesson#24 - Observer Design Pattern/ourGame/source/menu.d

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+module menu;
+
+import data;
+
+class Menu: IState {
+	this() {}
+
+	// inherited from IState interface
+	void run() {
+		writeln("*** menu state ***");
+	}
+}

lesson#24 - Observer Design Pattern/ourGame/source/play.d

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+module play;
+
+import data;
+
+class Play: IState {
+	this() {}
+
+	// inherited from IState interface
+	void run() {
+		writeln("*** play state ***");
+	}
+}