From: Robert Klemme <bob.news@...>
Date: 2004-12-02T22:42:44+09:00
Subject: Re: singleton methods : when are they not permitted?


"Brian Schr�der" <ruby@brian-schroeder.de> schrieb im Newsbeitrag
news:20041202141630.4a975ff1@black.wg...
> On Thu, 2 Dec 2004 21:27:43 +0900
> "Robert Klemme" <bob.news@gmx.net> wrote:
>
> > [snip]
> > But
> >
> > >> 2.times do |i| puts /abc#{i}/o.id end
> > 135012888
> > 135012888
> > => 2
> >
> > Note the usage of flag "o".
> >
> > Kind regards
> >
> >     robert
> >
>
> Interesting, but what is the use case for this? It seems to be quite
dangerous
> because it makes code really difficult to understand.

It's an optimization flag.  It's for those cases where you need
interpolation in a regexp but you know it will never change again.  This
is usual in little scripts, like

fake-grep.rb

rx = ARGV.shift
while ( line = gets )
  puts line if /#{rx}/o =~ line
end

I think Ruby inherited this flag from P**l.

Note: of course you can achieve the same with this little change:

rx = /#{ARGV.shift}/
while ( line = gets )
  puts line if rx =~ line
end

> E.g. The causual reader would expect this to yield nil, 0, nil.
>
> > 3.times do | i | puts /#{i}/o =~ '1' end
> nil
> nil
> nil
> => 3
>
> I shall read my pickaxe again ;)

:-)

Regards

    robert