From: Robert Klemme <shortcutter@...>
Date: 2008-09-08T23:43:36+09:00
Subject: Re: regular expression match and exclude

2008/9/8 Patrick He <patrick.he@gmail.com>:
> Maybe you can write the regex pattern like this:
>
> irb(main):022:0> imgs.each do |s|
> irb(main):023:1*   p [s, /^galleries\/((?!thumb).)+\.jpg$/ =~ s]
> irb(main):024:1> end
> ["galleries/blah.jpg", 0]
> ["galleries/blahthumb.jpg", nil]
> ["galleries/landscape.jpg", 0]
> ["galleries/landscapethumb.jpg", nil]
> ["galleries/foo.jpg", 0]
> ["galleries/foothumb.jpg", nil]
> => ["galleries/blah.jpg", "galleries/blahthumb.jpg",
> "galleries/landscape.jpg", "galleries/landscapethumb.jpg",
> "galleries/foo.jpg", "galleries/foothumb.jpg"]

Good idea!  But

irb(main):001:0> /^galleries\/((?!thumb).)+\.jpg$/ =~ "galleries/athumbb.jpg"
=> nil

And this should not be the case.  I believe this one is better

irb(main):002:0> /^galleries\/((?!thumb\.jpg).)+\.jpg$/ =~
"galleries/athumbb.jpg"
=> 0

Also, you do not need the capturing group, so

irb(main):003:0> /^galleries\/(?:(?!thumb\.jpg).)+\.jpg$/ =~
"galleries/athumbb.jpg"
=> 0

Or even

irb(main):004:0> /^galleries\/(?:(?!thumb\.).)+\.jpg$/ =~
"galleries/athumbb.jpg"
=> 0

Kind regards

robert

-- 
use.inject do |as, often| as.you_can - without end