# Data-Oriented Design

> Generic operations on generic data structures beat specialized operations on specialized structures.

- Skill: `tools-only/data-oriented-design` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add tools-only/data-oriented-design`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tools-only/data-oriented-design/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: tools-only (https://skillmd.com/u/tools-only)
- Updated: 2026-09-29
- Page: https://skillmd.com/skills/tools-only/data-oriented-design

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# Data-Oriented Design

## The Core Principle

> "It is better to have 100 functions operate on one data structure than 10 functions on 10 data structures."

Generic operations on generic data structures beat specialized operations on specialized structures.

## Why Custom Abstractions Hurt

Every custom type, wrapper class, or specialized structure:
- Adds a concept to understand
- Requires its own operations
- Limits composition with other code
- Creates maintenance burden

A `Map<String, Value>` can be processed by hundreds of existing functions. A `SettingsManager` class can only be processed by the methods you write for it.

## Information Over Objects

Model the information domain, not the behavior.

- What data exists?
- What are the essential relationships?
- What transformations do you need?

Then use generic structures (maps, vectors, sets) to represent that information. The behavior comes from functions that operate on data - not from methods bound to custom objects.

## Practical Application

Before creating a new class/type, ask:
- Could this be a map/dict with well-known keys?
- Could this be a simple tuple/record?
- Do I need custom behavior, or just data?

If you just need data, use data structures. Save custom types for when you genuinely need custom behavior that can't be a function.

**The power is in the combinations, not the custom constructs.**

## External References

- [The Value of Values](https://www.infoq.com/presentations/Value-Values/) - Rich Hickey on data vs objects
- [Data-Oriented Design](https://www.dataorienteddesign.com/dodbook/) - Richard Fabian's book on DOD
- [CppCon 2014: Mike Acton "Data-Oriented Design"](https://www.youtube.com/watch?v=rX0ItVEVjHc) - Practical DOD in game engines