From: Andrew Wagner <wagner.andrew@...>
Date: 2011-01-07T04:56:36+09:00
Subject: Re: Class Initialization?

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On Thu, Jan 6, 2011 at 2:41 PM, Kedar Mhaswade <kedar.mhaswade@gmail.com>wrote:

> Andrew Wagner wrote in post #972567:
> > On Wed, Jan 5, 2011 at 12:18 PM, Kedar Mhaswade
> > <kedar.mhaswade@gmail.com>wrote:
> >
> >> available from the class, without having to create any instances of it.
> >>
> >> --
> >> Posted via http://www.ruby-forum.com/.
> >>
> >>
> > To answer this, grasshopper, I suggest you study this code, and figure
> > out
> > how it works. Hint: there are more than one @count variables.
> >
> > class Counter
> >   @count = 0
> >
> >   class << self
> >     attr_accessor :count
> >   end
> >
> >   def initialize
> >     self.class.count += 1
> >     @count = self.class.count
> >   end
> >
> >   def output
> >     puts "I am counter object number #{@count} of #{self.class.count}"
> >   end
> > end
> >
> > x = Counter.new
> > x.output # I am counter object number 1 of 1
> >
> > y = Counter.new
> > x.output # I am counter object number 1 of 2
> > y.output # I am counter object number 2 of 2
>
> My n00b parser is stuck at class << self for I have to yet learn that
> construct, I guess.
>
> But I will spend more time understanding this example. My first attempt
> tells me that there are two types of variables (one: class, other
> instance) and both are named count.
>
>
Well, there are two variables, on two different objects (the class and its
instance), but the point is that they're *not* two different types. They
work the same way, they're just on two different objects.

Here's a snipped that avoids the mean "class <<" stuff (with my apologies
for my laziness):

class Counter
  @count = 0

  def self.count
    @count
  end

  def self.count=(val)
    @count = val
  end

  def initialize
    self.class.count += 1
    @count = self.class.count
  end

  def output
    puts "I am counter object number #{@count} of #{self.class.count}"
  end
end

x = Counter.new
x.output # I am counter object number 1 of 1

y = Counter.new
x.output # I am counter object number 1 of 2
y.output # I am counter object number 2 of 2


 I am still influenced by the "initially straightforward" example given
> in the Pickaxe book that counts the number of Song objects created thus
> far (i.e. incrementing @@count by 1 in the initialize method).
>
> Thank you.
>
> --
> Posted via http://www.ruby-forum.com/.
>
>

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