How does this pattern maintain backward compatibility?

Because the constructor uses a variadic slice of options, you can add new 'With*' functions over time without changing the function signature of the constructor, meaning existing code never breaks.

When should I use Functional Options over a Config Struct?

Use Functional Options for public APIs with 3 or more optional parameters or when you expect the API to grow. Config Structs are better suited for simple, internal APIs where options rarely change.

Why use an interface instead of a closure for options?

The interface approach is preferred because it allows options to be compared in tests, facilitates easier debugging through the Stringer interface, and allows for more complex logic than simple closures.

Can this pattern handle required parameters?

Absolutely. Idiomatic Go practice suggests passing required parameters as standard arguments first, followed by the variadic slice of optional functional options.

Does this skill follow the Uber Go Style Guide?

Yes, the implementation patterns are specifically distilled from the Uber Style Guide and Google's internal Go coding standards for production software.

Go Functional Options Pattern

Name: Go Functional Options Pattern
Author: cxuu

bycxuu

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API開発

Implements idiomatic, extensible, and type-safe functional options patterns for Go constructors and factory functions.

This skill provides domain-specific guidance for implementing the Functional Options pattern in Go, distilled from the Uber Style Guide and Google's production best practices. It helps developers move beyond cluttered constructors and fragile config structs by implementing a robust pattern involving unexported options structs and exported Option interfaces. This approach ensures your Go APIs remain backward-compatible even as new configuration parameters are added, providing a clean caller experience while maintaining high testability and strict type safety.

主な機能

01Standardizes the creation of variadic With* option functions

02Implements the interface-based approach for superior testability and mockability

03Enforces clear separation between required parameters and optional settings

04Ensures API backward compatibility for future-proof library design

05Automates unexported options structs with sensible default values

0657 GitHub stars

ユースケース

01Building production-grade clients or database connectors following Uber's Go style guide

02Refactoring complex constructors with 3+ arguments into clean, readable functional options

03Designing public Go libraries that require extensible configuration without breaking changes

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add cxuu/golang-skills go-functional-options

For use in Claude.ai and ChatGPT

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