From: Peter Zotov <whitequark@...>
Date: 2012-09-10T09:13:31+09:00
Subject: Re: Need help with my logic

sharmin malik писал 10.09.2012 01:55:
>> unless myname =~ /\A(\w+-v)([khv])(-\d+\..+)\z/
>>   raise "Bad hostname format: #{myname.inspect}"
>> end
>> hosts = [$1+"k"+$3, $1+"h"+$3, $1+"v"+$3]
>> unless hosts.delete myname
>>   raise "Can't find my hostname #{myname.inspect} to remove from
>> #{hosts.inspect}"
>> end
>> hosts.each do |host|
>>   puts "Please connect to #{host}"
>> end
>
> HI this is  nice way to do ..
> but system hostname is like this (i forgot put -dk )
>
> dk-vk-2.-dk.domain.lan
>
> I tried to change the Regix.. but not working
> Can you please modify it little bit ??
> also would be able to explain me little bit how the regix is related 
> to
>  [$1+"k"+$3, $1+"h"+$3, $1+"v"+$3] ??
> thanks

Parts of strings which are matched by capturing groups (parenthesized
groups of symbols in regexen) are assigned to $-variables. For example,
look at this code:

"test 123 abc" =~ /test (..)3 ([ba]+)/
puts "$1,$2" # outputs 12,ab

The $N numeric variables are function-local and always refer to the 
last
regex executed in the current function. There is an effectively 
infinite
number of them.

You can make regex groups non-capturing by placing ?: in the beginning 
of
the group. E.g. ([ba]+) is capturing, and (?:[ba]+) is non-capturing.
Non-capturing groups behave in exactly same way as capturing ones, but
they do not have a corresponding $N-variable.

-- 
   WBR, Peter Zotov.