Template Method Design Pattern in C#

Back to Template Method description

Defines the skeleton of an algorithm in an operation, deferring some steps to subclasses. Template Method lets subclasses redefine certain steps of an algorithm without changing the algorithm's structure.

This structural code demonstrates the Template method which provides a skeleton calling sequence of methods. One or more steps can be deferred to subclasses which implement these steps without changing the overall calling sequence.

using System;

  class MainApp
  {
    static void Main()
    {
      AbstractClass c;
 
      c = new ConcreteClassA();
      c.TemplateMethod();

      c = new ConcreteClassB();
      c.TemplateMethod();

      // Wait for user 
      Console.Read();
    }
  }

  // "AbstractClass"
  abstract class AbstractClass
  {
    public abstract void PrimitiveOperation1();
    public abstract void PrimitiveOperation2();

    // The "Template method" 
    public void TemplateMethod()
    {
      PrimitiveOperation1();
      PrimitiveOperation2();
      Console.WriteLine("");
    }
  }

  // "ConcreteClass" 
  class ConcreteClassA : AbstractClass
  {
    public override void PrimitiveOperation1()
    {
      Console.WriteLine("ConcreteClassA.PrimitiveOperation1()");
    }
    public override void PrimitiveOperation2()
    {
      Console.WriteLine("ConcreteClassA.PrimitiveOperation2()");
    }
  }

  class ConcreteClassB : AbstractClass
  {
    public override void PrimitiveOperation1()
    {
      Console.WriteLine("ConcreteClassB.PrimitiveOperation1()");
    }
    public override void PrimitiveOperation2()
    {
      Console.WriteLine("ConcreteClassB.PrimitiveOperation2()");
    }
  }
ConcreteClassA.PrimitiveOperation1()
ConcreteClassA.PrimitiveOperation2()

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