From: Simon Strandgaard <neoneye@...>
Date: 2004-09-20T19:08:35+09:00
Subject: Re: Ruby nuby -- modifying Regexp casefold

On Monday 20 September 2004 10:59, Luca Pireddu wrote:
> Hi all.  I have just started playing with Ruby and I'm stuck on something. 
> Is there some trick to modify the casefold attribute of a Regexp object
> after it's been instantiated?

when Regexp has been instantiated, then you cannot modify it.
There is no way to modify a regexp instance.


> The best idea I've had is the following:
> irb(main):001:0> a = Regexp.new('a')
> => /a/
> irb(main):002:0> aA = Regexp.new(a.to_s, Regexp::IGNORECASE)
> => /(?-mix:a)/i

(?-i) turns off ignorcase mode..


> But it doesn't seem to work:
> irb(main):003:0> a =~ 'a'
> => 0
> irb(main):004:0> a =~ 'A'
> => nil
> irb(main):005:0> aA =~ 'a'
> => 0
> irb(main):006:0> aA =~ 'A'
> => nil

maybe try this if you want line 006 to return an index
aA=Regexp.new('(?i)'+a.source)


> Something I don't understand is happening here.  Where did the 'i' go on
> line 14?
> irb(main):013:0> aA = Regexp.new(a.to_s, Regexp::IGNORECASE)
> => /(?-mix:a)/i

ruby 1.8.1 outputs   => /(?i-mx:a)/
something must have been changed with 1.8.2
the output on line 14 is wrong.

> irb(main):014:0> aA.to_s
> => "(?-mix:a)"
> irb(main):015:0>
>
> I'm using Ruby 1.8.2 (2004-08-24) [i386-linux], irb 0.9(02/07/03) on
> Debian.

--
Simon Strandgaard