如果评估的最后一个语句是 If 语句，Ruby 会返回什么 [英] What is Returned in Ruby if the Last Statement Evaluated is an If Statement

问题描述

我的理解是 ruby​​ 返回函数中评估的最后一条语句.如果函数以 if 语句结束，结果为 false

My understanding is that ruby returns the last statement evaluated in a function. What if the function ends with an if statement that evaluates to false

def thing(input)
  item = input == "hi"
  if item
    []
  end
end

puts thing("hi").class #> Array
puts thing("not hi").class #> NilClass

我喜欢这个功能(如果语句为 false，则返回 nil)，但为什么不返回 false(从赋值给 item)?

I like this functionality (returning nil if the statement is false), but why isn't false returned (from the assignment to item)?

推荐答案

如果你的 if 语句没有运行任何代码，则返回 nil，否则返回运行的代码.Irb 是试验这些东西的好工具.

If your if statement doesn't result in any code being run, it returns nil, Otherwise, it returns the value of the code that was run. Irb is a good tool to experiment with such stuff.

irb(main):001:0> i = if false then end
=> nil
irb(main):002:0> i = if true then end
=> nil
irb(main):007:0> i = if false then "a" end
=> nil
irb(main):008:0> i = if false then "a" else "b" end
=> "b"

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