gof-patterns
Skill17 starsChanged 9 months agoMITView on GitHub
Gang of Four design patterns reference. Use this skill when implementing, discussing, or choosing object-oriented design patterns. Auto-activates for architecture decisions, refactoring, and decoupling concerns. Comprehensive coverage of all 23 GoF patterns with pseudocode examples.
1 other project uses a version of this.
Adopted by
Most recently taken up by
- robconery/koleatheir own version, first seen Aug 19, 2026
Other versions1 project uses a version of this.
Word for word · 0
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None found.
Wrote their own version · 1
- robconery/kolea★ 7same name
How matches are found. Word for word: the exact same text. Edited: shares passages with this file (“99% same” means 99% of its five-word phrases also appear here; 10% or more counts). Their own version: similar meaning, or, weakest, the same name. We can’t tell which project had it first. Projects are counted among the 200 most-starred candidates, and mentions are links to the repository we found, up to 50 per site, so both counts are a floor.
In this repository7 other files it gives its agents.
- clean-codeSkill
- clrs-algorithmsSkill
- dddSkill
- ddiaSkill
- pragmatic-programmerSkill
- sicpSkill
- software-patternsSkill
The file
We split this skill into the rules it gives an agent
5 rules. About 0 are common, 5 are distinctive, and 0 are very specific to this project.
≈0
Common · estimate
Many files like this have a rule of this kind.
≈5
Distinctive · estimate
This author's own choices. Worth a look.
0
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Distinctive: line 13
Ask about or need to implement a design pattern
- Distinctive: line 62
Choosing a pattern: Start with the decision guide or tables above
- Distinctive: line 63
Learning a pattern: Read the full documentation with examples
- Distinctive: line 64
Quick reminder: Use the tables above for at-a-glance reference
- Distinctive: line 65
Implementation: Follow the pseudocode, adapt to your language
≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
GoF Design Patterns Reference
A comprehensive reference for the Gang of Four design patterns. This skill provides language-agnostic guidance with pseudocode examples that can be translated to any programming language.
When This Skill Activates
This skill automatically activates when you:
- Ask about or need to implement a design pattern
- Need to choose between patterns for a design problem
- Are refactoring code and considering structural improvements
- Discuss architecture, decoupling, or extensibility
- Mention specific patterns: factory, singleton, observer, decorator, etc.
Quick Pattern Reference
Creational Patterns (Object Creation)
| Pattern | Intent | Use When |
| Abstract Factory | Create families of related objects | Need platform/theme independence |
| Builder | Construct complex objects step-by-step | Object has many optional parts |
| Factory Method | Let subclasses decide which class to instantiate | Don't know concrete types ahead of time |
| Prototype | Clone existing objects | Object creation is expensive |
| Singleton | Ensure single instance | Need exactly one shared instance |
Structural Patterns (Composition)
| Pattern | Intent | Use When |
| Adapter | Convert interface to expected interface | Integrating incompatible interfaces |
| Bridge | Separate abstraction from implementation | Need to vary both independently |
| Composite | Treat individual and groups uniformly | Have tree structures |
| Decorator | Add responsibilities dynamically | Need flexible extension |
| Facade | Simplified interface to subsystem | Complex subsystem needs simple API |
| Flyweight | Share common state efficiently | Many similar objects needed |
| Proxy | Control access to object | Need lazy loading, access control, logging |
Behavioral Patterns (Communication)
| Pattern | Intent | Use When |
| Chain of Responsibility | Pass request along handler chain | Multiple handlers, unknown which handles |
| Command | Encapsulate request as object | Need undo, queue, or log operations |
| Interpreter | Define grammar and interpret sentences | Have a simple language to parse |
| Iterator | Sequential access without exposing internals | Need to traverse collections |
| Mediator | Centralize complex communications | Many objects communicate in complex ways |
| Memento | Capture and restore object state | Need undo/snapshot functionality |
| Observer | Notify dependents of state changes | One-to-many dependency |
| State | Alter behavior when state changes | Object behavior depends on state |
| Strategy | Encapsulate interchangeable algorithms | Need to swap algorithms at runtime |
| Template Method | Define skeleton, let subclasses fill in | Algorithm structure fixed, steps vary |
| Visitor | Add operations without changing classes | Need to add many operations to stable structure |
Decision Guide
See Pattern Selection Guide for help choosing the right pattern.
How to Use This Reference
- Choosing a pattern: Start with the decision guide or tables above
- Learning a pattern: Read the full documentation with examples
- Quick reminder: Use the tables above for at-a-glance reference
- Implementation: Follow the pseudocode, adapt to your language
Language Translation Notes
The pseudocode in this reference uses these conventions:
classfor type definitionsfunctionfor methods/functions->for method calls on objects//for comments- Type hints shown as
name: Type
Translate to your language:
- PHP:
class,function,->,//, type hints in docblocks or PHP 8+ - JavaScript/TypeScript:
class,function/arrow,.,//, TS types - Python:
class,def,.,#, type hints - Java/C#: Direct mapping with
new, generics
Based on concepts from "Design Patterns: Elements of Reusable Object-Oriented Software" by Gamma, Helm, Johnson, and Vlissides (Gang of Four), 1994.
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