Go Patterns

This skill provides comprehensive Go patterns extending common design principles with Go-specific idioms.

Functional Options

Use the functional options pattern for flexible constructor configuration:

type Option func(*Server)

func WithPort(port int) Option {
    return func(s *Server) { s.port = port }
}

func NewServer(opts ...Option) *Server {
    s := &Server{port: 8080}
    for _, opt := range opts {
        opt(s)
    }
    return s
}

Benefits:

• Backward compatible API evolution
• Optional parameters with defaults
• Self-documenting configuration

Small Interfaces

Define interfaces where they are used, not where they are implemented.

Principle: Accept interfaces, return structs

// Good: Small, focused interface defined at point of use
type UserStore interface {
    GetUser(id string) (*User, error)
}

func ProcessUser(store UserStore, id string) error {
    user, err := store.GetUser(id)
    // ...
}

Benefits:

• Easier testing and mocking
• Loose coupling
• Clear dependencies

Dependency Injection

Use constructor functions to inject dependencies:

func NewUserService(repo UserRepository, logger Logger) …