Add Template (ES5 + ES6 + CoffeeScript + TypeScript)

Author: Badacadabra

doc/GoF/Behavioral/Template/README.md

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+# Synopsis
+
+I am a construction professional and I always respect the basic principles of my job. I build houses and buildings following the common sense.
+
+# Problem
+
+Building something like a house is not trivial. It is very technical and, if you are not a construction professional, you may do things in the wrong order. For example, you could be tempted to build walls on a ground that is not fully prepared, leading to weak foundations.
+
+# Solution
+
+Even for professionals, it is good to have a template (like a plan drawn by an architect). This template makes it clear that you have to work on foundations first, then build walls and finally put the roof.
+
+The Template design pattern is an ideal candidate to express with code this kind of situation. For this pattern, we need:
+
+  * An abstract representation of a construction (abstract class is preferred because it makes it possible to implement the template method which will be the same for every type of construction)
+  * Concrete constructions (House & Building)
+
+Most methods on the abstract class are abstract and are implemented in concrete constructions.

doc/GoF/Behavioral/Template/Template.dia

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+# ==============================
+# ABSTRACT HOME 
+# ==============================
+
+class Home
+    constructor: ->
+        throw new Error "You cannot instantiate an abstract class!" if @constructor is Home
+
+    foundations: ->
+        throw new Error "You cannot call an abstract method!"
+
+    walls: ->
+        throw new Error "You cannot call an abstract method!"
+
+    roof: ->
+        throw new Error "You cannot call an abstract method!"
+
+    build: ->
+        """
+        Construction of a new home:
+         1. #{this.foundations()}
+         2. #{this.walls()}
+         3. #{this.roof()}\n
+        """
+
+# ==============================
+# CONCRETE HOMES 
+# ==============================
+
+class House extends Home
+    foundations: ->
+        "House foundations"
+
+    walls: ->
+        "House walls"
+
+    roof: ->
+        "House roof"
+
+class Building extends Home
+    foundations: ->
+        "Apartment building foundations"
+
+    walls: ->
+        "Apartment building walls"
+
+    roof: ->
+        "Apartment building roof"
+
+# ==============================
+# CLIENT CODE
+# ==============================
+
+house = new House
+building = new Building
+
+console.log house.build()
+console.log building.build()

doc/GoF/Behavioral/Template/Template.png

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+// ==============================
+// ABSTRACT HOME 
+// ==============================
+
+abstract class Home {
+    public abstract foundations(): string;
+    public abstract walls(): string;
+    public abstract roof(): string;
+
+    public build(): string {
+        return `
+Construction of a new home:
+ 1. ${this.foundations()}
+ 2. ${this.walls()}
+ 3. ${this.roof()}`;
+    }
+}
+
+// ==============================
+// CONCRETE HOMES 
+// ==============================
+
+class House extends Home {
+    public foundations(): string {
+        return "House foundations";
+    }
+
+    public walls(): string {
+        return "House walls";
+    }
+
+    public roof(): string {
+        return "House roof";
+    }
+}
+
+class Building extends Home {
+    public foundations(): string {
+        return "Apartment building foundations";
+    }
+
+    public walls(): string {
+        return "Apartment building walls";
+    }
+
+    public roof(): string {
+        return "Apartment building roof";
+    }
+}
+
+// ==============================
+// CLIENT CODE
+// ==============================
+
+let house: Home = new House(),
+    building: Home = new Building();
+
+console.log(house.build());
+console.log(building.build());

src/CoffeeScript/GoF/Behavioral/Template/Template.coffee

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+'use strict';
+
+// ==============================
+// ABSTRACT HOME 
+// ==============================
+
+var Home = (function() {
+    function Home() {
+        if (this.constructor === Home) {
+            throw new Error("You cannot instantiate an abstract class!");
+        } 
+    }
+
+    Home.prototype.foundations = function () {
+        throw new Error("You cannot call an abstract method!");
+    };
+
+    Home.prototype.walls = function () {
+        throw new Error("You cannot call an abstract method!");
+    };
+
+    Home.prototype.roof = function () {
+        throw new Error("You cannot call an abstract method!");
+    };
+
+    Home.prototype.build = function () {
+        var home = "";
+        home += "Construction of a new home:\n";
+        home += " 1. " + this.foundations();
+        home += " 2. " + this.walls();
+        home += " 3. " + this.roof();
+        return home;
+    };
+
+    return Home;
+})();
+
+// ==============================
+// CONCRETE HOMES 
+// ==============================
+
+var House = (function () {
+    function House() {}
+    House.prototype = Object.create(Home.prototype);
+    House.prototype.constructor = House;
+
+    House.prototype.foundations = function () {
+        return "House foundations\n";
+    };
+
+    House.prototype.walls = function () {
+        return "House walls\n";
+    };
+
+    House.prototype.roof = function () {
+        return "House roof\n";
+    };
+
+    return House;
+})();
+
+var Building = (function () {
+    function Building() {}
+    Building.prototype = Object.create(Home.prototype);
+    Building.prototype.constructor = Building;
+
+    Building.prototype.foundations = function () {
+        return "Apartment building foundations\n";
+    };
+
+    Building.prototype.walls = function () {
+        return "Apartment building walls\n";
+    };
+
+    Building.prototype.roof = function () {
+        return "Apartment building roof\n";
+    };
+
+    return Building;
+})();
+
+// ==============================
+// CLIENT CODE
+// ==============================
+
+var house = new House(),
+    building = new Building();
+
+console.log(house.build());
+console.log(building.build());

src/TypeScript/GoF/Behavioral/Template/Template.ts

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+// ==============================
+// ABSTRACT HOME 
+// ==============================
+
+class Home {
+    constructor() {
+        if (new.target !== undefined) {
+            throw new Error("You cannot instantiate an abstract class!");
+        } 
+    }
+
+    foundations() {
+        throw new Error("You cannot call an abstract method!");
+    }
+
+    walls() {
+        throw new Error("You cannot call an abstract method!");
+    }
+
+    roof() {
+        throw new Error("You cannot call an abstract method!");
+    }
+
+    build() {
+        return `
+Construction of a new home:
+ 1. ${this.foundations()}
+ 2. ${this.walls()}
+ 3. ${this.roof()}`;
+    }
+}
+
+// ==============================
+// CONCRETE HOMES 
+// ==============================
+
+class House extends Home {
+    foundations() {
+        return "House foundations";
+    }
+
+    walls() {
+        return "House walls";
+    }
+
+    roof() {
+        return "House roof";
+    }
+}
+
+class Building extends Home {
+    foundations() {
+        return "Apartment building foundations";
+    }
+
+    walls() {
+        return "Apartment building walls";
+    }
+
+    roof() {
+        return "Apartment building roof";
+    }
+}
+
+// ==============================
+// CLIENT CODE
+// ==============================
+
+let house = new House(),
+    building = new Building();
+
+console.log(house.build());
+console.log(building.build());