From: Jacob Fugal <lukfugl@...>
Date: 2006-04-20T02:05:44+09:00
Subject: Re: Is there an "in" operator in ruby ?

On 4/19/06, Dirk Meijer <hawkman.gelooft@gmail.com> wrote:
> @test=[2,4,6,8]
>
> (1..10).each do |n|
>   if @test.include?(n)
>     #execute code
>   end
> end

On 4/19/06, Matthew Moss <matthew.moss.coder@gmail.com> wrote:
> Why all that when:
>
> @test.each do |n|
>    # execute code
> end

Ah, but what if @test includes elements not in the original loop? Eg:

  @test=[2,4,6,8,13]

  (1..10).each do |n|
    if @test.include?(n)
      #execute code
    end
  end
  # => executed for 2, 4, 6, 8

  @test.each do |n|
     # execute code
  end
  # => executed for 2, 4, 6, 8, 13

But, in agreeance with other posters in the thread, I'd actually use
some set arithmetic:

  ([*1..10] & @test).each do |n|
    # execute code
  end

Of course, this assumes that the elements of the outer loop are known
in advance, as opposed to being generated in a while loop, a
non-expanded large range, etc.

Jacob Fugal