On May 4, 3:11 ¨Âí¬ Òïâåòô Ëìåííå ¼óèïòôãõô®®®Àçïïçìåíáéì®ãïí¾ ÷òïôåº
> On 03.05.2008 18:00, lovea... / gmail.com wrote:
>
> > I am not sure if this is possible. I have a case statement which
> > checks for a regular expression. For example:
>
> > case text
> > when /(abc)(.)*/
> > when /(xyz)(.)*/
> > end
>
> > In the above snippet how can I use the instance variables pre_match
> > and post_match? I tried calling these methods without any qualifiers
> > but I got a NoMethodError. Where does Ruby store the MatchData if the
> > matching is done in a case statement?
>
> $ irb
> irb(main):001:0> /b/ =~ "abc"
> => 1
> irb(main):002:0> $`
> => "a"
> irb(main):003:0> $'
> => "c"
> irb(main):004:0> $~
> => #<MatchData:0x7ff9eb54>
> irb(main):005:0> $~.to_a
> => ["b"]
> irb(main):006:0> $~.pre_match
> => "a"
> irb(main):007:0> $~.post_match
> => "c"
> irb(main):008:0>
>
> But why do you have groups in your regular expressions if you are not
> interested in the content?  ¨Âì󢨮©ª¢ óååíâéïäâåãáõóéô íéçèôïùéåì÷èáô ùïåøðåãô>
> irb(main):008:0> /a(.)*/ =~ "abcdef"
> => 0
> irb(main):009:0> $1
> => "f"
>
> IMHO it is generally a bad idea to use grouping in the way you do it
> because it will capture a lot that you are not interested in.  ¨Âóååí> you might rather want "(.*)".
>
> Kind regards
>
> robert

Hey Robert,

In my guess /b/ =~ "abc" is what sets $~ variable. Since I am not
using that statement anywhere that variable is not set at all. Instead
I am doing the matching in a case statement. As a result I am not able
to do something like $~.pre_match. I am not fond of $1, $2, etc
variables. I feel comfortable using the instance variables pre_match
and post_match.

But you solved the first problem I was trying to solve :) I was using
(.)* instead of (.*) and I couldn't get what I wanted. (.*) is what I
needed. Thanks so much for that. Now I can use $1, $2 at least if not
pre_match and post_match.

-subbu