Prototype Pattern: Copying a Slide Template

The Prototype Pattern lets you make new objects by copying existing ones, instead of building them from the start each time. This is useful when you have many objects that share the same set-up.

It is often used when creating objects is slow or complicated. Cloning an existing object is much faster and makes sure that every copy is just right.

Real-Life Analogy: Copying a Slide Template

Imagine you're preparing a presentation. You already have a well-designed slide that has the right colours, fonts, and layout. Rather than designing a new slide from scratch, you just duplicate the existing slide and update the content.

That's exactly what the Prototype Pattern does in code — it lets you clone an object that has already been set up. It's faster, safer, and makes sure everything looks and behaves the same way.

Benefits of Prototype Pattern

Sometimes creating an object is expensive or complicated. You may have to set lots of fields or connect to other systems. By using a prototype, you can skip the setup and just make a copy of something that already works.

It's also useful when you don't know the exact type of object you'll need until runtime.

• Makes object creation fast and flexible
• Avoids complex setup logic
• Reduces code duplication when objects share structure

What to Implement

To implement the Prototype Pattern, you need:

An interface or base class that defines a method for cloning. Then, concrete classes implement this method by returning a copy of themselves.

• Prototype Interface: Declares a method like Clone()
• Concrete Classes: Implement the clone method to copy themselves

How It Works in C#

// Prototype Interface
public interface ISlide
{
    ISlide Clone();
    void Show();
}

// Concrete Implementation
public class TitleSlide : ISlide
{
    public string Title { get; set; }

    public ISlide Clone()
    {
        return new TitleSlide { Title = this.Title };
    }

    public void Show()
    {
        Console.WriteLine($"Title Slide: {Title}");
    }
}

Usage:

ISlide original = new TitleSlide { Title = "Welcome!" };
ISlide copy = original.Clone();

original.Show();
copy.Show();

When Should You Use It?

Use the Prototype Pattern when the cost of creating a new object is high — either in time, memory, or complexity. It works well when objects have many configuration steps or are based on runtime data.

It is especially helpful when:

• You need many copies of similar objects
• The object type is decided at runtime
• You want to reduce direct dependency on concrete classes

When Not to Use It: Avoid this pattern if objects are simple or have no shared configuration. In that case, just create a new instance directly.

Where Is It Used in the Real World?

The Prototype Pattern is useful wherever new objects are created by copying existing ones, rather than building from scratch. It's common in document editors, UI components, and games.

• Document editing (duplicate slides, pages, objects)
• Game development (cloning preconfigured characters or units)
• Prototyping complex UI components
• Serialization/deserialization (deep copies of objects)

Final Thoughts

The Prototype Pattern is like copying a slide. You don't rebuild the design from scratch — you just copy, tweak, and use it again.

It keeps your code clean and avoids repeating setup logic. Whenever you need a fresh version of something you already have, clone it with a prototype.