From: Robert Klemme <bob.news@...>
Date: 2006-02-22T22:08:32+09:00
Subject: Re: A regexp for an include? method

Boucher, Eric <eric.boucher@messier-dowty.com> wrote:
> Hi,
>
> I want to see if a certain pattern is inside an array. I tried:
> myArray.flatten.include?(/myPattern/)
>
> but it always return false. Why? Is it because the "include?" doesn't
> takes regular expressions?
> Here's another example that I tried inside an irb session:
>
> data = ["TC_TP1", "TC_TP2", "TC_TP3"]
> =>["TC_TP1", "TC_TP2", "TC_TP3"]
> data.include?(/TC_TP/)
> => false
> data.include?(/TC_TP.*/)
> => false
> data.include?(/TC_TP1/)
> => false
> data.include?("TC_TP1")
> => true !!!
>
> Thanks for your help.

It's because include? uses #eql? or == for comparison while regexp matching 
is done via === and =~.  You can use #find, #select or #any?

irb(main):042:0> data.find {|x| /TC_TP/ =~ x}
=> "TC_TP1"
irb(main):043:0> data.find {|x| /XTC_TP/ =~ x}
=> nil
irb(main):044:0> data.select  {|x| /XTC_TP/ =~ x}
=> []
irb(main):045:0> data.select  {|x| /TC_TP/ =~ x}
=> ["TC_TP1", "TC_TP2", "TC_TP3"]
irb(main):046:0> data.any?  {|x| /TC_TP/ =~ x}
=> true
irb(main):047:0> data.any?  {|x| /YTC_TP/ =~ x}
=> false

I'd go for any? as it short circuits, i.e. terminates after the first 
successful match.

Kind regards

    robert