What is the Abstract Factory Pattern?

The Abstract Factory pattern is a creational design pattern that provides an interface for creating families of related objects without specifying their concrete classes. It enables you to ensure that the created objects work together consistently, while maintaining loose coupling between client code and the objects being created.

🏗 Common Use Cases

• Cross-Platform UI Libraries – Create consistent UI elements across different operating systems or themes.
• Database Access Layers – Switch between different database providers without changing application code.
• Game World Generation – Create consistent game environments with matching terrain, characters, and objects.

When Should You Avoid Abstract Factory?

While the Abstract Factory pattern is powerful for creating families of related objects, it might not always be the best choice:

❌ Simple Object Creation – If you only need to create a single type of object, consider using Factory Method instead.
❌ Excessive Flexibility – Adding unnecessary abstraction layers when your product variations are unlikely to change.
❌ Maintenance Overhead – Every new product variant requires changes across multiple factory interfaces and implementations.

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Implementing Abstract Factory in C#

Let’s implement the Abstract Factory pattern with a real-world example: a cross-platform UI toolkit that needs to create consistent UI controls for different operating systems.

// Abstract Product Interfaces
public interface IButton
{
    void Render();
    void HandleClick();
}

public interface ITextBox
{
    void Render();
    void HandleInput(string text);
}

// Concrete Products - Windows Family
public class WindowsButton : IButton
{
    public void Render()
    {
        Console.WriteLine("Rendering a button in Windows style");
    }
    
    public void HandleClick()
    {
        Console.WriteLine("Windows button clicked");
    }
}

public class WindowsTextBox : ITextBox
{
    public void Render()
    {
        Console.WriteLine("Rendering a textbox in Windows style");
    }
    
    public void HandleInput(string text)
    {
        Console.WriteLine($"Windows textbox input: {text}");
    }
}

// Concrete Products - MacOS Family
public class MacOSButton : IButton
{
    public void Render()
    {
        Console.WriteLine("Rendering a button in MacOS style");
    }
    
    public void HandleClick()
    {
        Console.WriteLine("MacOS button clicked");
    }
}

public class MacOSTextBox : ITextBox
{
    public void Render()
    {
        Console.WriteLine("Rendering a textbox in MacOS style");
    }
    
    public void HandleInput(string text)
    {
        Console.WriteLine($"MacOS textbox input: {text}");
    }
}

// Abstract Factory Interface
public interface IUIControlFactory
{
    IButton CreateButton();
    ITextBox CreateTextBox();
}

// Concrete Factories
public class WindowsUIControlFactory : IUIControlFactory
{
    public IButton CreateButton()
    {
        return new WindowsButton();
    }

    public ITextBox CreateTextBox()
    {
        return new WindowsTextBox();
    }
}

public class MacOSUIControlFactory : IUIControlFactory
{
    public IButton CreateButton()
    {
        return new MacOSButton();
    }

    public ITextBox CreateTextBox()
    {
        return new MacOSTextBox();
    }
}

// Client code
public class Application
{
    private readonly IButton _button;
    private readonly ITextBox _textBox;
    
    public Application(IUIControlFactory factory)
    {
        _button = factory.CreateButton();
        _textBox = factory.CreateTextBox();
    }
    
    public void RenderUI()
    {
        _button.Render();
        _textBox.Render();
    }
}

// Usage example
public class Program
{
    public static void Main()
    {
        // Determine the operating system
        bool isWindows = Environment.OSVersion.Platform == PlatformID.Win32NT;
        
        // Create appropriate factory
        IUIControlFactory factory = isWindows 
            ? new WindowsUIControlFactory() 
            : new MacOSUIControlFactory();
        
        // Create and use the application with the selected factory
        var app = new Application(factory);
        app.RenderUI();
    }
}

Key Benefits of the Abstract Factory Pattern

1. Consistency Guarantee – Ensures that products from the same family always work together.
2. Encapsulation – Isolates concrete classes from client code, reducing coupling.
3. Replaceable Product Families – Switch between different implementations by changing the factory instance.
4. Single Responsibility Principle – Extracts product creation code from the business logic.

Abstract Factory vs. Factory Method

While both are creational patterns, they solve different problems:

Abstract Factory	Factory Method
Creates families of related objects	Creates a single object
Multiple creation methods per factory	Single creation method
Client works with multiple product types	Client works with a single product type
Focuses on product compatibility	Focuses on deferring instantiation to subclasses

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Final Thoughts

The Abstract Factory pattern provides a powerful way to create families of related objects while maintaining loose coupling between client code and concrete implementations. When implemented correctly, it enhances code maintainability, scalability, and flexibility.

Remember that this pattern shines in scenarios where you need to ensure compatibility across product families, but comes with the cost of increased complexity. As with any design pattern, consider your specific requirements carefully.