Prototype
Use the current instance of a type to create a same instance with the Clone but not new.
When we use this pattern
I have no idea now, need to dig more in the future.
Roles in this pattern
- Prototype: define an interface used to clone itself
- ConcretePrototype: implement the interface of the Prototype and what's more, implement the Clone method to make the self-clone.
- Client:Use the ConcretePrototype to clone itself.
Demo
namespace Prototype { public abstract class Prototype { private string id; public string Id { get { return this.id; } } public Prototype(string id) { this.id = id; } public abstract Prototype Clone(); } public class ConcretePrototype : Prototype { public ConcretePrototype(string id) : base(id) { } public override Prototype Clone() { return (Prototype)this.MemberwiseClone(); } } public class Client { static void Main(string[] args) { ConcretePrototype c1 = new ConcretePrototype("me"); ConcretePrototype c2 = (ConcretePrototype)c1.Clone(); Console.WriteLine(c2.Id);//show "me" here } } }
This is a common example to demonstrate this pattern, but in ASP.NET, you don't need to do like this, because there is an interface called as ICloneable available.
The ICloneable is equivalent to the Prototype defined above. So in ASP.NET, you can simplify the example above like below:
namespace Prototype { public class ConcretePrototype : ICloneable { private string id; public string Id { get { return this.id; } } public ConcretePrototype(string id) { this.id = id; } public object Clone() { return (Object)this.MemberwiseClone(); } } public class Client { static void Main(string[] args) { ConcretePrototype c1 = new ConcretePrototype("me"); ConcretePrototype c2 = (ConcretePrototype)c1.Clone(); Console.WriteLine(c2.Id);//show "me" here } } }
The new version is simpler and briefer than the old one with the help of the inherent interface.
there are two concepts we got to know:
- Shallow copy
- Deep copy
I don't wanna detail them know here, can google or read the book