From: Robert Dober <robert.dober@...>
Date: 2007-08-24T06:11:03+09:00
Subject: Re: Once more unto the breach: private class methods

On 8/23/07, Zeekar <markjreed@gmail.com> wrote:
> Found a lot of discussion of this, but it didn't seem to suggest a
> solution to a common pattern.  The below completely useless example is
> modeled after a longer and more useful one in the Agile Web
> Development with Rails book (2nd ed):
>
> class Foo
>     class << self
>           private
>           def staticHelperFunction
>                12345
>           end
>     end
>     public
>     def initialize
>          @var = self.class.staticHelperFunction
>     end
> end
> Foo.new.var
>
> Now, the above won't work, obviously.  If I replace the direct call to
> staticHelperFunction with instance_eval or send, it will work, but
> that feels hackish.   Is there an idiomatic Ruby way to handle this
> sort of situation?
>
> In case the goal isn't clear, I want instance (not singleton/class)
> methods of a given class to have access to what are essentially helper
> functions/subroutines (not other instance methods of the same class)
> which are not generally accessible outside of that class.
>
> Doable?
Sure, but clumsy, I do not know if it is worth it

class Foo
  class << self
    private
    def x; 60 end
  end
  attr_reader :x
  helper = method(:x)
  define_method :initialize do @x = helper.call end
end

puts Foo.new.x

HTH
Robert
>
>
>


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other people.
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