[C#]Design Pattern for .NET Programmers

#NOTE: Youtube link: http://youtu.be/S8XL1L_1Lyw

  • Abstract Factory
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{
public static Object Create(string className, Dictionary<String, Object> values)
{
Type type = Type.GetType(className);
Object instance = Activator.CreateInstance(type);
foreach (var entry in values)
{
type.GetProperty(entry.Key).SetValue(instance, entry.Value, null);
}
return instance;
}
static void Main(string[] args)
{
Console.WriteLine(Create("Patterns.Book", new Dictionary<string, object>()
{
{"Title", "Some titles"},
{"Pages", 100}
}));

Console.WriteLine(Create("Patterns.CD", new Dictionary<string, object>()
{
{"Title", "Some CD"},
{"Volume", 12}
}));
}
}

class Book
{
public string Title { get; set; }
public int Pages { get; set; }
public override string ToString()
{
return string.Format("Book {0} {1}", Title, Pages);
}
}

class CD
{
public string Title { get; set; }
public int Volume { get; set; }
public override string ToString()
{
return string.Format("CD {0} {1}", Title, Volume);
}
}
}
  • Cascade Pattern
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{

static void Main(string[] args)
{
// Sect I
//Mailer mailer = new Mailer();
//mailer.from("[email protected]");
//mailer.to("[email protected]");
//mailer.subject("subjeccccttt");
//mailer.message("contents blah blah");
//mailer.send();

// Sect II- Cascade way
new Mailer().from("[email protected]")
.to("[email protected]")
.subject("subjeccccttt")
.message("contents blah blah")
.send();
}
}
// Sect I
//class Mailer
//{
// public void to(string toAdrr) { }
// public void from(string fromAddr) { }
// public void subject(string sub){}
// public void message(string msg) { }
// public void send() { }
//}

// Sect II
class Mailer
{
public Mailer to(string toAdrr) { return this; }
public Mailer from(string fromAddr) { return this; }
public Mailer subject(string sub) { return this; }
public Mailer message(string msg) { return this; }
public void send() { }
}
}
  • Pluggable Behavior
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{
static int totalValues(int[] values)
{
int total = 0;
foreach (var value in values)
{
total += value;
}
return total;
}
static int totalEvenValues(int[] values)
{
int total = 0;
foreach (var value in values)
{
if (value % 2 == 0) total += value;
}
return total;
}
static int totalOddValues(int[] values)
{
int total = 0;
foreach (var value in values)
{
if (value % 2 != 0) total += value;
}
return total;
}
static int totalSelectValues(int[] values, Func<int, bool> selector)
{
int total = 0;
foreach (var value in values)
{
// pass value(first param) into function and return second param value
if (selector(value)) total += value;
}
return total;
}
//
static void Main(string[] args)
{
int[] values = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };

Console.WriteLine(totalValues(values));
Console.WriteLine(totalEvenValues(values));
Console.WriteLine(totalOddValues(values));

Console.WriteLine("==================");
// re-write
// define functioin in lambda format
// ref: http://msdn.microsoft.com/zh-tw/library/bb397687(v=vs.110).aspx
Console.WriteLine(totalSelectValues(values, (value) => true));
Console.WriteLine(totalSelectValues(values, (value) => value % 2 == 0));
Console.WriteLine(totalSelectValues(values, (value) => value % 2 != 0));
}
}
}
  • Execute Around Method Pattern

part1

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{
class Resource
{
public Resource()
{
Console.WriteLine("Creating...");
}
public void op1()
{
Console.WriteLine("op1...");
}
public void op2()
{
Console.WriteLine("op2...");
}
~Resource()
{
Console.WriteLine("cleanup exensive resource");
}

}
public static void Main(string[] args)
{
{
Resource resource = new Resource();
resource.op1();
resource.op2();
}
Console.WriteLine("out of the block");
}
}
}

執行結果: 執行結果

part2 (with using())

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{
class Resource : IDisposable
{
public Resource()
{
Console.WriteLine("Creating...");
}
public void op1()
{
Console.WriteLine("op1...");
}
public void op2()
{
Console.WriteLine("op2...");
}
~Resource()
{
Clearnup();
}
public void Dispose()
{
Clearnup();
GC.SuppressFinalize(this);
}
private void Clearnup()
{
Console.WriteLine("cleanup exensive resource");
}
}
public static void Main(string[] args)
{
// this require class that implement IDisposable
using (Resource resource = new Resource())
{
resource.op1();
resource.op2();
}
Console.WriteLine("out of the block");
}
}
}

執行結果

part3 with Execute Around Method Pattern

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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Patterns
{
class Program
{
class Resource
{
//Call Resource class from here
public static void Use(Action<Resource> block)
{
Resource resouce = new Resource();
try
{
block(resouce);
}
finally
{
resouce.Clearnup();
}

}

//change public to protected
// can't new class in normal way : class _class = new class()
protected Resource()
{
Console.WriteLine("Creating...");
}

public void op1()
{
Console.WriteLine("op1...");
}
public void op2()
{
Console.WriteLine("op2...");
}

private void Clearnup()
{
Console.WriteLine("cleanup exensive resource");
}
}
public static void Main(string[] args)
{
{
Resource.Use(
(resource) =>
{
resource.op1();
resource.op2();
});
}
Console.WriteLine("out of the block");
}
}
}

執行結果