go-functional-options

Source : Uber Go Style Guide Functional options is a pattern where you declare an opaque Option type that records information in an internal struct. The constructor accepts a variadic number of these options and applies them to configure the result. Use functional options when: The unexported apply method ensures only options from this package can be used. Source : Uber Go Style Guide Source : Uber Go Style Guide Prefer Config Struct when : Fewer than 3 options, options rarely change, all options usually specified together, or internal APIs only. Source : Uber Go Style Guide An alternative implementation uses closures: The interface approach is preferred because: - 3+ optional arguments on constructors or public APIs - Extensible APIs that may gain new options over time - Clean caller experience is important (no need to pass defaults) - Unexported options struct - holds all configuration - Exported Option interface - with unexported apply method - Option types - implement the interface - With* constructors - create options - Testability - Options can be compared in tests and mocks - Debuggability - Options can implement fmt.Stringer - Flexibility - Options can implement additional interfaces - Visibility - Option types are visible in documentation - go-style-core - Core Go style principles - go-naming - Naming conventions for Go - go-defensive - Defensive programming patterns...