From: Jeremy McAnally <jeremymcanally@...>
Date: 2008-10-04T04:43:34+09:00
Subject: Re: class << self

None of them are really better; they all do the same thing. :)

The first and second approaches (to me) make it easier to discern, at
a glance, what's a class method and what's an instance method.  On the
other hand, the last one (class << self) keeps you from re-typing the
class name/self over and over again.

--Jeremy

On Fri, Oct 3, 2008 at 2:36 PM, Patrick Doyle <wpdster@gmail.com> wrote:
> Sorry if this is a FAQ, but I was just looking at some Ruby code and
> came across the following construct:
>
> class << self
>  def blahblahblah
>  ...
>  end
> end
>
> I wondered what that did, went looking, and came across this email
> thread from 2002:
> http://blade.nagaokaut.ac.jp/cgi-bin/scat.rb/ruby/ruby-talk/57244, in
> reading that, I came across this (slightly modified) code:
>
> class A
>  B = 12
>  def self.a
>    puts "class method A::a : #{B}"
>  end
>
>  def A.b
>    puts "class method A::b : #{B}"
>  end
>
>  class << self
>    B = 24
>    def c
>      puts "class method A::c : #{B}"
>    end
>  end
>
> end
> A.a
> A.b
> A.c
> puts "A::B : #{A::B}"
>
> Could somebody enlighten me as to what is going on here?  I didn't
> completely follow all of the ins & outs of the thread, nor why
>
> def self.a
>
> is better/different than
>
> def A.a
>
> is better different than
>
> class << self
>  def a
>
> Can anybody comment or point me in the direction of some enlightenment?
>
> --wpd
>
>



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