deps

Overview ¶

Package deps documents the dependency injection pattern used across hawk.

Pattern ¶

Each package that needs external dependencies defines a Deps struct with exported fields for each dependency. A zero value means "use default". Constructors accept the deps struct and fill in defaults for zero fields.

Example:

type LoggerDeps struct {
    Output io.Writer  // default: os.Stderr
    Level  Level      // default: Info
}

func NewWithDeps(deps LoggerDeps) *Logger {
    if deps.Output == nil {
        deps.Output = os.Stderr
    }
    return &Logger{level: deps.Level, output: deps.Output}
}

Tests override individual fields:

var buf bytes.Buffer
log := logger.NewWithDeps(logger.LoggerDeps{Output: &buf})

This replaces positional constructor arguments and makes testing explicit. Keep legacy constructors (e.g., New(output, level)) as convenience wrappers that call NewWithDeps internally.