From: Ian Macdonald <ian@...>
Date: 2007-02-14T05:19:59+09:00
Subject: Puzzling regex behaviour

Hello,

Can anyone explain this to me?

$ echo $LANG
nl_NL
$ irb -f
irb(main):001:0> foo = "pr�f�r�es"
=> "pr\351f\351r\351es"
irb(main):002:0> foo =~ /[^[:alnum:]]/
=> nil
irb(main):003:0> foo =~ /\W/
=> 2

First question: Why does the final statement return 2 instead of nil?
All characters in foo are alphabetic characters in this locale.

Then:

$ echo $LANG
nl_NL
$ cat ./foo
#!/usr/bin/ruby -w

foo = "pr�f�r�es"
p foo =~ /[^[:alnum:]]/
p foo =~ /\W/
$ ./foo
2
2

Huh?

Second question: Why does the first regex match now return 2 instead of
nil?

To my way of thinking, both statements should always return nil, whether
or not they are typed into irb or run in a stand-alone script. At the
very least, both statements should return the same answer, regardless of
the context.

What am I missing here?

Ian
-- 
Ian Macdonald               | tachyon emissions overloading the system 
ian@caliban.org             | 
http://www.caliban.org/     | 
                            | 
                            |