ruby - 百分比运算符，字符串插值

Question

这是 Zed Shaw 书中的一些代码:

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."
}

我理解%{}默认是%Q{}，也就是字符串插值。但是双引号里面的%{}是什么意思呢？

"%{first} %{second} %{third} %{fourth}"

这行是什么意思？

puts formatter % {first: 1, second: 2, third: 3, fourth: 4}

Answer 1

两者都与 %Q 无关。

formatter 和 hash 之间的 % 是 String#%方法。

"%{first} %{second} %{third} %{fourth}" 是格式字符串，参见 Kernel#sprintf了解详情。