So when I was coding, I wanted a simpler, more organized way to handle responsibilities and make the contract between components clearer. Patterns like Strategy or Facade work fine in theory, but trying to manage multiple responsibilities often felt messy and fragile.

That’s when I started experimenting with what I now call the Reflective Delegate Pattern. After reading feedback and thinking back on my previous post, I consider this a definitive version of the idea.

It’s a bit philosophical and experimental, and not always easy to show clearly in code. Some strict SOLID advocates might disagree, but I find it a helpful way to think about modularity, responsibility management, and runtime organization in a slightly unconventional way.

I call this approach the Reflective Delegate Pattern.

Core idea

• Each entity (or facade) implements the same interfaces that its delegates provide.
• Delegates encapsulate all logic and data, adhering to these interfaces.
• The entity basically acts as a mirror, forwarding calls directly to its delegates.
• Delegates can be swapped at runtime without breaking the entity or client code.
• Each delegate maintains a single responsibility, following SOLID principles wherever possible.

Why it works

Cliients only interact with the interfaces, never directly with the logic.
The entity itself doesn’t “own” the logic or data; it simply mirrors the API and forwards calls to its delegates.
This provides modularity, polymorphism, and clean decoupling.

It’s like a Facade + Strategy, but here the Facade implements the same interfaces as its delegates, effectively reflecting their behavior.

Essentially, it’s a specialized form of the Delegate Pattern: instead of a single delegate, the entity can handle multiple responsibilities dynamically, while keeping its API clean and fully polymorphic.

Here’s an example:

Reflective Delegate Pattern
https://github.com/unrays

// Interfaces
interface IPrintable { void print(String msg); }
interface ISavable { void save(String msg); }

// Delegates 
class Printer implements IPrintable { 
    @Override public void print(String msg) { System.out.println("Printing: " + msg); }
}

class Saver implements ISavable {
     @Override public void save(String msg) { System.out.println("Saving: " + msg); } 
}

// Entity reflecting multiple interfaces
class DocumentService implements IPrintable, ISavable {    
    IPrintable printDelegate;
    ISavable saveDelegate;

    @Override public void print(String msg) { printDelegate.print(msg); }
    @Override public void save(String msg) { saveDelegate.save(msg); }  
}

// Usage
public class Main {
    public static void main(String[] args) {
        DocumentService docService = new DocumentService();

        docService.printDelegate = new Printer();
        docService.saveDelegate = new Saver();

        docService.print("Project Plan");
        docService.save("Project Plan");

        docService.printDelegate = (msg) -> System.out.println("Mock printing: " + msg);
        docService.print("Test Document");
    }
}

Key takeaways

• The Reflective Delegate Pattern enables flexible runtime modularity and polymorphism.
• Each delegate handles a single responsibility, keeping components clean and focused.
• The entity acts as a polymorphic proxy, fully hiding implementation details.
• Based on the Delegate Pattern, it supports multiple dynamic delegates transparently.
• Provides a clear approach for modular systems that require runtime flexibility.
• Feedback, improvements, or references to similar patterns are welcome.

Tags: #ReflectorPattern #DelegatePattern #SoftwareArchitecture #DesignPatterns #CleanArchitecture #SOLIDPrinciples #ModularDesign #RuntimePolymorphism #HotSwap #DynamicDelegation #Programming #CodeDesign #CodingIsLife