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Prototype Pattern

Prototype Pattern 


Gamma Categorization: Creational Design Patten
Summary: When the object construction reiterate existing designs. Its a partially or fully initialized object that you copy (clone) and make use of.

Sample Code

Problem: we need to create a Point object, that may be either Cartesian or Polar.

Custom Prototype Interface

public interface IPrototype<T>
{
    T DeepCopy();
}

public class DigitalCamera : IPrototype<DigitalCamera>
{
    public string Brand { get; set; }
    public string Model { get; set; }
    public DateTime Year { get; set; }

    public override string ToString() => $"Brand: {Brand}, Model: {Model}, Year: {Year}";

    public DigitalCamera DeepCopy()
    {
        return new DigitalCamera 
        {
            Brand = this.Brand,
            Model = this.Model,
            Year = this.Year
        };
    }
}

Usage

var camera = new DigitalCamera();
camera.Brand = "Canon";
camera.Model = "70D";
camera.Year = new System.DateTime(2013,1,1);

var camera2 = camera.DeepCopy();
camera2.Model = "80D";
camera2.Year = new System.DateTime(2016,1,1);
WriteLine(camera);
WriteLine(camera2);

Output
Brand: Canon, Model: 70D, Year: 01/01/2013 00:00:00
Brand: Canon, Model: 80D, Year: 01/01/2016 00:00:00

Serialized Copy Through Extension Interface

[Serializable]
public class DigitalCamera
{
    public string Brand { get; set; }
    public string Model { get; set; }
    public DateTime Year { get; set; }

    public override string ToString() => $"Brand: {Brand}, Model: {Model}, Year: {Year}";

}

public static class ExtensionMethods
{
    public static T DeepCopy<T>(this T self)
    {
        using (var ms = new MemoryStream())
        {
            var formatter = new BinaryFormatter();
            formatter.Serialize(ms, self);
            ms.Position = 0;

            return (T) formatter.Deserialize(ms);
        }
    }
}

Usage

var camera = new DigitalCamera();
camera.Brand = "Canon";
camera.Model = "70D";
camera.Year = new System.DateTime(2013,1,1);

var camera2 = camera.DeepCopy();
camera2.Model = "80D";
camera2.Year = new System.DateTime(2016,1,1);
WriteLine(camera);
WriteLine(camera2);

Output
Brand: Canon, Model: 70D, Year: 01/01/2013 00:00:00
Brand: Canon, Model: 80D, Year: 01/01/2016 00:00:00

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