design-patterns-skill

What I do

I help you identify and apply appropriate design patterns:

1. Pattern Recognition: Identify when a design pattern is the right solution
2. Prevent Over-Engineering: Avoid forcing patterns where they don't belong
3. Apply Creational Patterns: Singleton, Factory, Builder, Prototype
4. Apply Structural Patterns: Adapter, Decorator, Proxy, Composite
5. Apply Behavioral Patterns: Strategy, Observer, Template Method, Command
6. Refactor to Patterns: Let patterns emerge from refactoring, not upfront design

When to use me

Use this skill when:

• You have a design problem and wonder if a pattern applies
• Code has repeated type-checking or switch statements
• You need to add behavior without modifying existing code
• Objects need to be created with complex configuration
• Multiple objects need to be treated uniformly
• You're tempted to add a pattern but unsure if it's needed

Do NOT use this skill when:

• You want to add patterns "just in case"
• The simple solution works fine
• You're designing before you have a real problem

Prerequisites

• Understanding of object-oriented programming
• Knowledge of interfaces and abstractions
• Familiarity with basic refactoring techniques
• A real design problem to solve (not hypothetical)

What Are Design Patterns?

Reusable solutions to common design problems. A shared vocabulary for discussing design.

WARNING: Don't Force Patterns

"Let patterns emerge from refactoring, don't force them upfront."

Patterns should solve problems you HAVE, not problems you MIGHT have.

When to Use Patterns

1. You recognize the problem - You've seen it before
2. The pattern fits - Not forcing it
3. It simplifies - Doesn't add unnecessary complexity
4. Team understands it - Shared knowledge

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Creational Patterns

Singleton

Purpose: Ensure only one instance exists.

When to use: Global configuration, connection pools, logging.

Warning: Often overused. Consider dependency injection instead.