Extract Helpers

Skill: Extract Helpers to Limit Variable Scope

Flag: A local variable whose scope spans more of a function than it needs to — it's only used inside a self-contained block of logic.

Ask: Extract that block into a helper function. This limits the variable's lifetime to the helper, shortens the enclosing function, and makes the intent clearer.

Example

func Greeting(user User) string {
    name := strings.TrimSpace(user.FirstName)
    if name == "" {
        name = "friend"
    }
    name = strings.Title(name)

    return fmt.Sprintf("Hello, %s! You have %d new messages.", name, user.Unread)
}

name is built up over three lines, then used once. Its scope spans the whole function for no reason. Real code tends to have more extreme versions of this.

vs.

func displayName(user User) string {
    name := strings.TrimSpace(user.FirstName)
    if name == "" {
        return "friend"
    }
    return strings.Title(name)
}

func Greeting(user User) string {
    return fmt.Sprintf("Hello, %s! You have %d new messages.", displayName(user), user.Unread)
}

name now lives only inside displayName, and Greeting is a single expressive line.