From: 7stud -- <bbxx789_05ss@...>
Date: 2011-08-29T10:51:01+09:00
Subject: Re: String#split resets regex captures variables (Ruby 1.8.7)

Olivier Lance wrote in post #1018967:
> Hi,
>
> I've just spent some time on this problem until I found the solution,
> and I wanted to share it/ask for opinions on this:
>
> I've got a string on which I try to match a regexp. If it matches, I
> split the string with one of the captured groups, zip the resulting
> array with an array of symbols and merge with a last symbol/string array
> pair representing the captured separator.
>
> Here's some code to give you an idea:
>
> n = "a:c"
> if n =~ /([a-z])([.:])([a-z])/
>   p [:first, :second].zip(n.split($2)) | [[:separator, $2]]
> end
>
> (see pastie here: http://pastie.org/2445983)
>

Do you actually consider that a lucid example of the problem?  Bejeesus.

>
> The problem is, the resulting array will contain "nil" for :separator.
> Apparently, String#split will reset all regexp-related variables... I
> guess it uses regexp internally, but I haven't seen anything documenting
> this behavior, and I honestly believed this code would work...
>
> So what's your take on this? Does it feel natural/logical to you?
> Should I file a bug to enhance Ruby's documentation?


$ cat ruby.rb
str = 'abcd'

if str =~ /(c)(d)/
  p [$1, $2]
  str.split('b')
  p [$1, $2]
end

$ multiruby ruby.rb
/Users/me/.rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/ZenTest-4.5.0/lib/multiruby.rb:330: 
warning: shadowing outer local variable - s
/Users/me/.rvm/gems/ruby-1.9.2-p180@rails3tutorial/gems/ZenTest-4.5.0/lib/multiruby.rb:391: 
warning: shadowing outer local variable - s

VERSION = 1.8.6-p420
CMD     = ~/.multiruby/install/1.8.6-p420/bin/ruby ruby.rb

["c", "d"]
[nil, nil]

RESULT = pid 3744 exit 0

VERSION = 1.8.7-p352
CMD     = ~/.multiruby/install/1.8.7-p352/bin/ruby ruby.rb

["c", "d"]
[nil, nil]

RESULT = pid 3745 exit 0

VERSION = 1.9.1-p431
CMD     = ~/.multiruby/install/1.9.1-p431/bin/ruby ruby.rb

["c", "d"]
["c", "d"]

RESULT = pid 3746 exit 0

VERSION = 1.9.2-p290
CMD     = ~/.multiruby/install/1.9.2-p290/bin/ruby ruby.rb

["c", "d"]
["c", "d"]

RESULT = pid 3747 exit 0

TOTAL RESULT = 0 failures out of 4

Passed: 1.8.6-p420, 1.8.7-p352, 1.9.1-p431, 1.9.2-p290
Failed:
$

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