ruby - 当使用 ruby​​ 定义一系列键时，将所有键值作为组合字符串获取

Question

我有以下代码

class MyClass

  def my_method(first,last)
    #this should take 2 numbers as arguments and should return the keys value(s) as  a combined string
  end 
  private
     def lines_of_code 
      {
       1 => "This is first",
       2 => "This is second",
       3 => "This is third",
       4 => "This is fourth",
       5 => "This is fifth"
      }
     end
m = MyClass.new
m.my_method(2,4) # This is secondThis is thirdThis is fourth"

我应该将一个范围传递给 my_method，它反过来应该返回组合值字符串。抱歉，如果这已经发布。

提前致谢。

Answer 1

这是一个使用 Hash#values_at 的技巧:

class MyClass

  def my_method(first, last)
    lines_of_code.values_at(*first..last)
  end 

  private

  def lines_of_code 
    {
      1 => "This is first",
      2 => "This is second",
      3 => "This is third",
      4 => "This is fourth",
      5 => "This is fifth"
    }
  end
end

m = MyClass.new
p m.my_method(2,4)
# >> ["This is second", "This is third", "This is fourth"]
# to get a string
p m.my_method(2,4).join(" ")
# >> "This is second This is third This is fourth"