add factory method implementation

design_patterns/creational_patterns/factory_method/factory_method.cs

@@ -0,0 +1,70 @@
+using System;
+
+namespace designPatterns
+{
+ abstract class Creator
+ {
+ public abstract IProduct FactoryMethod();
+ public string Operation()
+ {
+ var product = FactoryMethod();
+ return $"Doing some work with {product.Operation()}";
+ }
+ }
+ class ConcreteCreatorA : Creator
+ {
+ public override IProduct FactoryMethod()
+ {
+ return new ConcreteProductA();
+ }
+ }
+ class ConcreteCreatorB : Creator
+ {
+ public override IProduct FactoryMethod()
+ {
+ return new ConcreteProductB();
+ }
+ }
+ public interface IProduct
+ {
+ string Operation();
+ }
+ class ConcreteProductA : IProduct
+ {
+ public string Operation()
+ {
+ return "Result of productA";
+ }
+ }
+ class ConcreteProductB : IProduct
+ {
+ public string Operation()
+ {
+ return "Result of productB";
+ }
+ }
+ class Client
+ {
+ public void Main()
+ {
+ Console.WriteLine("start the app with ConcreteCreatorA.");
+ ClientCode(new ConcreteCreatorA());
+ Console.WriteLine();
+ Console.WriteLine("start the app with ConcreteCreatorB.");
+ ClientCode(new ConcreteCreatorB());
+ }
+ public void ClientCode(Creator creator)
+ {
+ Console.WriteLine($"Creators class doesn't matter, operations are the same\n{creator.Operation()}");
+ }
+ }
+
+ class Program
+ {
+ static void Main(string[] args)
+ {
+ new Client().Main();
+ }
+ }
+
+}