formatter = "%{first} %{second} %{third} %{fourth}"
puts formatter % {first: 1, second: 2, third: 3, fourth: 4}
puts formatter % {first: "one", second: "two", third: "three", fourth: "four"}
puts formatter % {first: true, second: false, third: true, fourth: false}
puts formatter % {first: formatter, second: formatter, third: formatter, fourth: formatter}
puts formatter % {
first: "I had this thing.",
second: "That you could type up right.",
third: "But it didn't sing.",
fourth: "So I said goodnight."
}创建格式化字符串通常用#{}，给多个值指定同一格式时%{}更好用。