From: Bertram Scharpf <lists@...>
Date: 2009-07-22T00:26:40+09:00
Subject: Re: *%w[..lib]

Hi,

Am Dienstag, 21. Jul 2009, 23:39:38 +0900 schrieb William Djingga:
> $:.unshift File.join(File.dirname(__FILE__), *%w[.. lib])
> 
> what does *%w mean in the line above?

An array expands to an argument list.

%w() is just an array:

  %w[foo bar baz] == [ "foo", "bar", "baz"]

Here is an example for an *argument list.

  def f a, b, *args
    puts args.inspect
  end

  f( :x, :y, "i", "j")
  # Output:
  #   ["i", "j"]

  ary = ["foo", "bar"]
  f( :x, :y, *ary)
  # Output:
  #   ["foo", "bar"]

So the call will expand to

  $:.unshift File.join(File.dirname(__FILE__), "..", "lib")

These will work as well:

  ary = %w(a b c)
  [ "foo", "bar", *ary]     #=> ["foo", "bar", "a", "b", "c"]

  case somestr
    when *ary                then do_sth
    when *%w(quit exit bye)  then break
  end

Bertram


-- 
Bertram Scharpf
Stuttgart, Deutschland/Germany
http://www.bertram-scharpf.de