update factory method

Author: tk-codes

CreationalPatterns/FactoryMethod/README.md

@@ -6,6 +6,16 @@ A factory method
 * handles object creation and
 * encapsulates it in a subclass.
 
+## Problem
+
+* Object should be created so that subclasses can redefine which class to instantiate.
+* A class should defer instantiation to subclasses.
+
+## Solution
+
+* Define a separate operation `factory method` for creating object.
+* Create an object by calling a factory method.
+
 **Definition**
 ```cs
         // A facotry method
@@ -16,19 +26,9 @@ A factory method
         protected abstract Pizza CreatePizza(PizzaType type);
 ```
 
-![Pizza Store with Factory Method](/Diagrams/FactoryMethod.png)
+## Benefits
 
-**Usage**
-```cs
-            PizzaStore americanStore = new AmericanPizzaStore();
-            Pizza pizza = americanStore.OrderPizza(PizzaType.Veggie);
-            Console.WriteLine("Esposito ordered a " + pizza.Name);
-            
-            // Italian Pizza Store
-            PizzaStore italianStore = new ItalianPizzaStore();
-            Pizza pizza = italianStore.OrderPizza(PizzaType.Cheese);
-            Console.WriteLine("Esposito ordered a " + pizza.Name);
-```
+## Drawbacks
 
 ## Common Structure
 
@@ -45,3 +45,18 @@ A factory method
   * overrides the abstract factory method to return an instance of a ConcreteProduct (eg. AmericanCheesePizza)
 
 _[Source: http://www.dofactory.com/net/factory-method-design-pattern]_
+
+## Example Usage
+
+![Pizza Store with Factory Method](/Diagrams/FactoryMethod.png)
+
+```cs
+            PizzaStore americanStore = new AmericanPizzaStore();
+            Pizza pizza = americanStore.OrderPizza(PizzaType.Veggie);
+            Console.WriteLine("Esposito ordered a " + pizza.Name);
+            
+            // Italian Pizza Store
+            PizzaStore italianStore = new ItalianPizzaStore();
+            Pizza pizza = italianStore.OrderPizza(PizzaType.Cheese);
+            Console.WriteLine("Esposito ordered a " + pizza.Name);
+```