Prototype Design Pattern: Everything You Need to Know

Introduction: Design patterns are reusable solutions to common problems in software design. One such pattern is the Prototype Design Pattern, which allows you to create new objects by cloning existing ones.

This article will explore the Prototype Design Pattern when to use it, real-world examples, advantages and disadvantages, UML diagram, and how to implement it with a complete code example in C#.

Prototype Design Pattern

The Prototype Design Pattern is a creational pattern that creates new objects by cloning existing ones. It allows you to avoid creating objects from scratch and instead copy an existing object to create a new one.

This pattern specifies the kinds of objects to create using a prototypical instance, and it creates new objects by copying this Prototype.

When Will We Need the Prototype Design Pattern?

You might consider using the Prototype Design Pattern in the following scenarios:

• When creating new objects is expensive and time-consuming.
• When a class cannot anticipate the type of objects it needs to create
• When a class wants to delegate the responsibility of object creation to another class

Real-World Example of Prototype Design Pattern

Suppose you have a game where you can create different types of units, such as archers, knights, and mages. Each unit has specific characteristics such as attack, defense, and speed.

Instead of creating each unit from scratch, you can use the Prototype Design Pattern to clone an existing unit and modify its attributes as needed.

Advantage of Prototype Pattern:

• It reduces the need for creating new objects from scratch, saving time and resources.
• It allows you to configure objects at runtime dynamically.
• It provides a way to isolate the client code from the complexity of object creation.

Disadvantages of prototype design pattern:

• It can lead to the creation of deep object hierarchies and complex object graphs.
• It can increase memory usage since objects are cloned instead of instantiated.
• Implementing natively can be challenging in languages that do not support object cloning.

Usage of Prototype Pattern:

The Prototype Design Pattern is commonly used in scenarios where object creation is expensive and time-consuming, and the system wants to delegate the responsibility of object creation to another class. We can also use the Prototype Design Pattern with other creational patterns, such as the Abstract Factory Pattern.

UML for Prototype Pattern:

The UML diagram for the Prototype Design Pattern includes the following elements:

• Prototype: An abstract class that defines the clone method.
• ConcretePrototype: A concrete implementation of the Prototype class that implements the clone method.
• Client: The class that uses the Prototype to create new objects.

Complete code Example of Prototype Design Pattern in C#

Here is an example of how to implement the Prototype Design Pattern in C#:

using System;

namespace PrototypePattern
{
    // Step 1: Create an abstract Prototype class that defines the clone method.
    abstract class Prototype
    {
        public abstract Prototype Clone();
    }
    // Step 2: Create concrete implementations of the Prototype class that implement the clone method.
    class ConcretePrototype : Prototype
    {
        public int Id { get; set; }
        public string Name { get; set; }

        public override Prototype Clone()
        {
            // Use the MemberwiseClone() method to create a shallow copy of the object.
            return (Prototype)this.MemberwiseClone();
        }
    }

    // Step 3: Create a client class that uses the Prototype to create new objects.
    class Client
    {
        private Prototype prototype;

        public Client(Prototype prototype)
        {
            this.prototype = prototype;
        }

        public Prototype MakeCopy()
        {
            return prototype.Clone();
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            // Step 4: In the client code, create an instance of the concrete Prototype class and clone it to create a new instance.
            ConcretePrototype prototype = new ConcretePrototype() { Id = 1, Name = "Prototype 1" };
            Client client = new Client(prototype);
            ConcretePrototype copy = (ConcretePrototype)client.MakeCopy();

            Console.WriteLine("Original Object: Id = {0}, Name = {1}", prototype.Id, prototype.Name);
            Console.WriteLine("Cloned Object: Id = {0}, Name = {1}", copy.Id, copy.Name);

            Console.ReadLine();
        }
    }
}

The ConcretePrototype class defines two properties in the above example: Id and Name.
The Clone() method creates a shallow copy of the object using the MemberwiseClone() method.
The client code creates an instance of the ConcretePrototype class and passes it to the Client constructor.

The MakeCopy() method then clones the Prototype to create a new instance.

The output of this program will be:

Original Object: Id = 1, Name = Prototype 1 
Cloned Object: Id = 1, Name = Prototype 1

Conclusion:

The Prototype Design Pattern is a useful design pattern that allows you to create new objects by cloning existing ones.

It can help you save time and resources by reducing the need to create new objects from scratch. However, it also has its disadvantages, such as increasing memory usage and creating complex object hierarchies. By understanding when to use this pattern and how to implement it, you can take benefit of its in your software development projects.

References: Wikipedia-Prototype design Pattern

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Shekh Ali

Meet Sheikh Ali, a skilled Software engineer and passionate a blogger. He enjoys sharing his expertise in C#, Java, SQL, Design Patterns, and other related topics through his writing. When he's not coding, Sheikh Ali can often indulge in his passions for reading books and fitness training.

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