From: Rob Biedenharn <Rob@...>
Date: 2007-03-14T05:23:58+09:00
Subject: Re: perl to ruby


On Mar 13, 2007, at 3:59 PM, Chad Perrin wrote:

> On Wed, Mar 14, 2007 at 04:46:43AM +0900, Martin DeMello wrote:
>> On 3/14/07, Chad Perrin <perrin@apotheon.com> wrote:
>>> On Tue, Mar 13, 2007 at 05:36:20PM +0900, Martin DeMello wrote:
>>>>
>>>> or for efficiency
>>>>
>>>> File.open("/etc/passwd", "r") {|f| id =
>>>> f.grep(/#{usr}/).first.split(/:/).at(2).to_i}
>>>
>>> . . . or for more readability:
>>>
>>>  File.open("/etc/passwd", "r") do |f|
>>>    id = f.grep(/#{usr}).first.split(/:/).at(2).to_i
>>>  end
>>>
>>> I'm sure greater readability can be had by rewriting that  
>>> entirely, but
>>> I found the multiline braces approach suboptimal, personally.  YMMV.
>>
>> And the fact that my paste put a line break where it did didn't help
>> :) that was supposed to be on one line - didn't realise how long it
>> had gotten.
>
> Hmm.  It should have occurred to me that was meant to be all one line.
>
> I think lines that long should usually be broken up for readability
> anyway.  Usually.
>
> -- 
> CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
> "The first rule of magic is simple. Don't waste your time waving your
> hands and hopping when a rock or a club will do." - McCloctnick the  
> Lucid
>

  File.open("/etc/passwd", "r") do |f|
    id = f.detect {|line| line =~ /\A#{usr}:/}.split(/:/)[2].to_i
  end

using grep will read all the lines, but detect will stop after  
finding the first line for which the block is true.  I also suggest  
bracketing your regexp with \A (beginning of string) and  
':' (separator in /etc/passwd) so searching for, say, "0", doesn't  
give you the root account.

You probably also want to rescue exceptions that will arise if the  
usr is not found.

-Rob

Rob Biedenharn		http://agileconsultingllc.com
Rob@AgileConsultingLLC.com