Ruby Method Arguments: Positional, Keyword, and Variable Arguments

def add(a, b)
  a + b
end

add(1, 2) # => 3

def connect(host, port = 5432)
  "#{host}:#{port}"
end

connect("db.local") # => "db.local:5432"

def sum(*args)
  args.sum
end

sum(1, 2, 3) # => 6

def create_user(name:, email:, admin: false)
  { name: name, email: email, admin: admin }
end

create_user(name: "Lin", email: "[email protected]")

def log_event(event:, **meta)
  { event: event, meta: meta }
end

log_event(event: "login", user_id: 10, ip: "127.0.0.1")

def point((x, y))
  x * y
end

point([3, 4]) # => 12

def wrapper(...)
  target(...)
end

def f(opts)
  opts
end

f(a: 1) # Hash

def g(a:)
  a
end

g(a: 1) # keyword

h1 = { name: "bill" }      # symbol key
h2 = { "name" => "bill" } # string key

def send_email(to:, subject:, body:, retry_count: 3, timeout: 5)
  # send logic
end

send_email(
  to: "[email protected]",
  subject: "Build Status",
  body: "All green",
  timeout: 10
)