From: Robert Klemme <shortcutter@...>
Date: 2007-04-29T01:10:07+09:00
Subject: Re: Output A File w/ Line Numbers?

On 28.04.2007 15:27, John Joyce wrote:
> 
> On Apr 28, 2007, at 9:50 PM, Robert Klemme wrote:
> 
>> On 28.04.2007 09:06, Robert Dober wrote:
>>> On 4/28/07, Robert Dober <robert.dober@gmail.com> wrote:
>>>> > love,
>>>> > John Joyce
>>>> >
>>>> >
>>>> ARGF.readlines.each_with_index{
>>>>    | line, idx |
>>>>   puts "%3d %s" % [ idx.succ, line ]
>>>> }
>>>> HTH
>>>> Robert
>>> But Robert's solution is nicer, I did not know about ARGF.lineno, and
>>> have overlooked his solution, sorry!
>>
>> :-)  Thank you!  Btw, you can also do ARGF.each_with_index so you do 
>> not have to read the whole file into mem before printing it.
>>
>> Kind regards
>>
>>     robert
> This .each_with_index seems to be an invaluable method... I'd like to 
> know more about it. Can anyone give a little more detail on how 
> each_with_index works? The pickaxe covered it too briefly for my feeble 
> mind, but clearly it's got legs.

There's not much to it.  It's defined in module Enumerable and yields 
the current element plus a count to the block.  You can imagine it 
implemented like this but of course it's written in C:

module Enumerable
   def ewi
     c=0
     each {|x| yield x, c; c+=1}
   end
end

Kind regards

	robert