decorator pattern
- by vbNewbie
I have a program that converts currency using a specific design pattern. I now need to take my converted result and using the decorator pattern allow the result to be converted to 3 different formats: 1 - exponential notation, rounded to 2 decimal points.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace Converter
{
public partial class Form1 : Form
{
// Setup Chain of Responsibility
Handler h1 = new USDHandler();
Handler h2 = new CADHandler();
Handler h3 = new AUDHandler();
public string reqCurName;
public int reqAmt;
public string results;
public string requestID;
public Form1()
{
InitializeComponent();
h1.SetSuccessor(h2);
h2.SetSuccessor(h3);
}
// "Handler"
private void button1_Click_1(object sender, EventArgs e)
{
reqCurName = txtInput.Text;
reqAmt = Convert.ToInt32(txtAmt.Text.ToString());
results = h1.HandleRequest(reqCurName, reqAmt);
if (results != "")
{
lblResult.Text = results;
lblResult.Visible = true;
}
}
abstract class Handler
{
protected Handler successor;
public string retrn;
public void SetSuccessor(Handler successor)
{
this.successor = successor;
}
public abstract string HandleRequest(string requestID, int reqAmt);
}
// "USD Handler"
class USDHandler : Handler
{
public override string HandleRequest(string requestID, int reqAmt)
{
if (requestID == "USD")
{
retrn = "Request handled by " +
this.GetType().Name + " \nConversion from Euro to USD is " + reqAmt/0.630479;
return (retrn);
}
else if (successor != null)
{
retrn = successor.HandleRequest(requestID, reqAmt);
}
return (retrn);
}
}
// "CAD Handler"
class CADHandler : Handler
{
public override string HandleRequest(string requestID, int reqAmt)
{
if (requestID == "CAD")
{
retrn = "Request handled by " +
this.GetType().Name + " \nConversion from Euro to CAD is " + reqAmt /0.617971;
return (retrn);
}
else if (successor != null)
{
retrn = successor.HandleRequest(requestID, reqAmt);
}
return (retrn);
}
}
// "AUD Handler"
class AUDHandler : Handler
{
public override string HandleRequest(string requestID, int reqAmt)
{
if (requestID == "AUD")
{
requestID = "Request handled by " +
this.GetType().Name + " \nConversion from Euro to AUD is " + reqAmt / 0.585386;
return (requestID);
}
else if (successor != null)
{
retrn = successor.HandleRequest(requestID, reqAmt);
}
return (requestID);
}
}
}
}
