From: 7stud -- <bbxx789_05ss@...>
Date: 2007-11-01T06:17:27+09:00
Subject: Re: why, or when to, use a class method?

Thufir wrote:
> Why a class variable?  All
> SongList objects will use the same method, but wouldn't they use the
> same method even if it were an instance method?  Methods are declared
> on the class, not the instance.
> 
> Why use a class method in the first example, though?

So that you can check whether a Song is too long without having to 
create a SongList object:

#---------
class Song
  attr_accessor :duration

  def initialize(len)
    @duration = len
  end
end



class SongList
  MaxTime = 5*60

  def SongList.isTooLong(aSong)
    return aSong.duration > MaxTime
  end
end

#------------

s = Song.new(10)
puts SongList.isTooLong(s)

Otherwise, you would have to write:

s = Song.new(10)
sl = SongList.new()
puts sl.isTooLong(s)


Does that make sense for this example?  Who knows.

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