From: Chris Carter <cdcarter@...>
Date: 2007-02-26T04:08:36+09:00
Subject: Re: Class method declarations help

On 2/25/07, Eckie Silapaswang <eckie2399@gmail.com> wrote:
> Hope everyone is having a great weekend!  I was looking over some code
> concerning class method declarations as shown below:
>
> #2
> class Animal
>   attr_accessor :species, :form
>
>   def self.create_from_hash(hash)
>     a = new
>     a.species = hash[:species]
>     a.form = hash[:form]
>     a
>   end
> end
> Animal::create_from_hash(:species => :fox, :form => :cartoon) # =>
>
> #3
> class Animal
>   attr_accessor :species, :form
>
>   class <<self
>     def create_from_hash(hash)
>       a = Animal.new
>       a.species = hash[:species]
>       a.form = hash[:form]
>       a
>     end
>   end
> end
> Animal::create_from_hash(:species => :fox, :form => :cartoon) # =>
>
> The lines of particular interest to me are the
>
> def self.create_from_hash(hash)
>
> and the
>
> class << self
>   def create_from_hash(hash)
>
> I remember reading from the "Ruby for Rails" book that there's a "subtle
> difference between these two approaches to defining a singleton method,
> involving the scope of constants, but that's an arcane point.  For the
> most part, you can treat them as equivalent".
>
> My questions to all the Rubyists out there is, do you have a particular
> preference between the two choices?  Is this a style issue?  Or is there
> really a concrete "it depends on this" factor?
>
> Best regards,
>
> Eckie
>
> --
> Posted via http://www.ruby-forum.com/.
>
>
Hi Eckie,
Generally speaking, if you only have 1 or 2 class methods you use the
self.method syntax, and if you have a lot of class methods you use the
class<<self syntax

-- 
Chris Carter
concentrationstudios.com
brynmawrcs.com