From: Rob Biedenharn <Rob@...>
Date: 2008-10-16T21:44:09+09:00
Subject: Re: symbol confusions!!

On Oct 16, 2008, at 8:07 AM, Jay Pangmi wrote:

> Hi, I'm new to ruby and I'm going thru pretty good as I've done java  
> but
> the only thing, at this point, thats really bothering me is the use of
> symbols like:
> %w{}
> %r{}
> %7d etc etc..
>
> So, is there anywhere I can find good discussions about such symbols  
> coz
> until now I'm using it blindly... thanks

Do you have a book like the Pickaxe?[1]  That will go into great  
detail on all the features that Ruby has to offer.

Briefly, however:

%w{} is a way to turn a list of words into an array:
  %w{ one fish two fish }
  => [ "one", "fish", "two", "fish" ]

%r{} is a regular expression literal.  %r{stuff.*} is like /stuff.*/  
without having to quote slashes (which is the main reason to see it  
used if you're matching a file path, for example)

%7d is probably a format specification from Kernel#sprintf or String#%  
meaning a decimal value in a minimum of 7 columns:
   "%7d"%42
   => "     42"

Oh, and "Kernel#sprintf" (generally, ClassName#method) means the  
instance method 'sprintf' from the class (or module) 'Kernel' (so, the  
'%' method from the String class).

-Rob


[1] http://www.pragprog.com/titles/ruby/programming-ruby


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