The Prototype design pattern specifies the kind of objects to create using a prototypical instance, and create new objects by copying this prototype.
A visualization of the classes and objects participating in this pattern.
The classes and objects participating in this pattern include:
ColorPrototype)
Color)
ColorManager)
This structural code demonstrates the Prototype pattern in which new objects are created by copying pre-existing objects (prototypes) of the same class.
copyusing System;
namespace Prototype.Structural
{
/// <summary>
/// Prototype Design Pattern
/// </summary>
public class Program
{
public static void Main(string[] args)
{
// Create two instances and clone each
ConcretePrototype1 p1 = new ConcretePrototype1("I");
ConcretePrototype1 c1 = (ConcretePrototype1)p1.Clone();
Console.WriteLine("Cloned: {0}", c1.Id);
ConcretePrototype2 p2 = new ConcretePrototype2("II");
ConcretePrototype2 c2 = (ConcretePrototype2)p2.Clone();
Console.WriteLine("Cloned: {0}", c2.Id);
// Wait for user
Console.ReadKey();
}
}
/// <summary>
/// The 'Prototype' abstract class
/// </summary>
public abstract class Prototype
{
string id;
// Constructor
public Prototype(string id)
{
this.id = id;
}
// Gets id
public string Id
{
get { return id; }
}
public abstract Prototype Clone();
}
/// <summary>
/// A 'ConcretePrototype' class
/// </summary>
public class ConcretePrototype1 : Prototype
{
// Constructor
public ConcretePrototype1(string id)
: base(id)
{
}
// Returns a shallow copy
public override Prototype Clone()
{
return (Prototype)this.MemberwiseClone();
}
}
/// <summary>
/// A 'ConcretePrototype' class
/// </summary>
public class ConcretePrototype2 : Prototype
{
// Constructor
public ConcretePrototype2(string id)
: base(id)
{
}
// Returns a shallow copy
public override Prototype Clone()
{
return (Prototype)this.MemberwiseClone();
}
}
}
This real-world code demonstrates the Prototype pattern in which new Color objects are created by copying pre-existing, user-defined Colors of the same type.
using System;
using System.Collections.Generic;
namespace Prototype.RealWorld
{
/// <summary>
/// Prototype Design Pattern
/// </summary>
public class Program
{
public static void Main(string[] args)
{
ColorManager colormanager = new ColorManager();
// Initialize with standard colors
colormanager["red"] = new Color(255, 0, 0);
colormanager["green"] = new Color(0, 255, 0);
colormanager["blue"] = new Color(0, 0, 255);
// User adds personalized colors
colormanager["angry"] = new Color(255, 54, 0);
colormanager["peace"] = new Color(128, 211, 128);
colormanager["flame"] = new Color(211, 34, 20);
// User clones selected colors
Color color1 = colormanager["red"].Clone() as Color;
Color color2 = colormanager["peace"].Clone() as Color;
Color color3 = colormanager["flame"].Clone() as Color;
// Wait for user
Console.ReadKey();
}
}
/// <summary>
/// The 'Prototype' abstract class
/// </summary>
public abstract class ColorPrototype
{
public abstract ColorPrototype Clone();
}
/// <summary>
/// The 'ConcretePrototype' class
/// </summary>
public class Color : ColorPrototype
{
int red;
int green;
int blue;
// Constructor
public Color(int red, int green, int blue)
{
this.red = red;
this.green = green;
this.blue = blue;
}
// Create a shallow copy
public override ColorPrototype Clone()
{
Console.WriteLine(
"Cloning color RGB: {0,3},{1,3},{2,3}",
red, green, blue);
return this.MemberwiseClone() as ColorPrototype;
}
}
/// <summary>
/// Prototype manager
/// </summary>
public class ColorManager
{
private Dictionary<string, ColorPrototype> colors =
new Dictionary<string, ColorPrototype>();
// Indexer
public ColorPrototype this[string key]
{
get { return colors[key]; }
set { colors.Add(key, value); }
}
}
}
The .NET optimized code demonstrates the
same real-world situation as above but uses modern, built-in .NET features,
such as, generics, reflection, LINQ, lambda functions, etc.
You can find an example on our Singleton pattern page.
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