From: Hassan Schroeder <hassan.schroeder@...>
Date: 2012-04-11T11:19:52+09:00
Subject: Re: less absolutely horrible way to make sure array 1 only contains elements from array 2?

On Tue, Apr 10, 2012 at 6:44 PM, ruby ismyname <lists@ruby-forum.com> wrote:

> I need to make sure that myselections only contains elements from
> choices, includes? doesn't work because it allows for partial matches.
> This works but it looks absolutely horrible.

I have to agree with that last sentence :-)

I'm not sure what 'partial matches' means in this context but maybe
this will be useful --

1.9.2-p290 :024 > choices = %w[a b c d e f g h i j k]
 => ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k"]
1.9.2-p290 :025 > selections = %w[c h k]
 => ["c", "h", "k"]
1.9.2-p290 :026 > bad_selections = %w[a b z]
 => ["a", "b", "z"]
1.9.2-p290 :027 > selections.drop_while{|selection| choices.include? selection }
 => []
1.9.2-p290 :028 > bad_selections.drop_while{|selection|
choices.include? selection }
 => ["z"]
1.9.2-p290 :029 > selections.drop_while{|selection| choices.include?
selection }.count > 0
 => false
1.9.2-p290 :030 > bad_selections.drop_while{|selection|
choices.include? selection }.count > 0
 => true

I'm sure this is also one of those TMTOWTDI cases :-)

-- 
Hassan Schroeder ------------------------ hassan.schroeder@gmail.com
http://about.me/hassanschroeder
twitter: @hassan