From: Tim Hunter <TimHunter@...>
Date: 2008-06-12T07:38:59+09:00
Subject: Re: Class (not instance) Initializer

Greg Willits wrote:
> I would like to populate a class variable using a method
> 
> class SomeThing
>   @@some_data
>   populate_some_data
> 
>   def populate_some_data
>   end
> end
> 
> 
> I expected that prefixing the method with self would work. It doesn't.
> 
>   ...
>   self.populate_some_data
> 
>   def self.populate_some_data
>   end
>   ...
> 
> Poking around in a couple books I don't see anything that addresses
> this. What's the correct syntax for this? Or, if there is no way to run
> a method, what's the best way to pull a trigger to have @@some_data
> populated the first time any object of SomeThings is instantiated?
> 
> -- gw

Well, if you want to wait to do the initialization until the first 
object is created, then something like this might work:

def initialize
   populate_some_data if @@some_data == nil
   ...
end

But if all you want to do it initialize @@some_data, just put the 
initialization code in the class definition:

class SomeThing
    @@some_data = [1,2,3]
    def initialize
      ...
    end
end

Ruby will execute the code as it creates the class. Try this:

~$ irb
irb(main):001:0> class SomeThing
irb(main):002:1>    puts "Hiya!"
irb(main):003:1> end
Hiya!
=> nil

-- 
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