Scaling isn't easy, it never was. Its not easy with any dynamic language. So, twitter as a rails application is facing some issues of scaling. So while I was sleeping peacefully, a war was going on, in the community. Alex, the twitter developer shares his thoughts, http://www.radicalbehavior.com/5-question-interview-with-twitter-developer-alex-payne/ and DHH retorts back, and criticizes arms-crossed approach, http://www.loudthinking.com/arc/000608.html.

So, what shall a rails developer learn from this. Well, just the basics that - any fool can code web pages, its not rocket science for sure. But how will he react when problems like these strike him? LiveJournal invented memcached, Google invented GFS, Wikipedia does this by aggressive caching. You can't get a out of box, scaling solution. This is the precise reason, Why I have been adamant about hiring people, who know ruby better, who can dig into the internals and come up with shiny code.

Dr Nic, comes with a solution, http://drnicwilliams.com/2007/04/12/magic-multi-connections-a-facility-in-rails-to-talk-to-more-than-one-database-at-a-time/, which is not exactly the same. But lets see. Oh and dev.rubyonrails.org is a python page, which had same problem with trac.

After trying out many crappy, CHM viewers in Linux, I have finally settled on kchmviewer.

A real nice app to use actually.

They have a factory that produces Singletons

As a kid, all I wanted to do is, play guitar and jump around, too many people got into my way.
—Syd Barret

We all know how evil class variables are, and they are as dangerous as the “three headed dog” at the dungeon and we shall not talk about it.

But they are necessary for many of the thingies ruby does and used extensively.But today we shall not talk about them.

We saw earlier that, although class instance variables are excellent, but not so friendly to use and they make Ruby look like C++(ahem).

Here goes a little hack, that allows you to define class level attributes based on class instance variables. Since, i often use it in rails and they have taken cattr for class level attributes.

class Object
  def self.metaclass; class << self; self; end; end
  def self.iattr_accessor *args
    metaclass.instance_eval do
      attr_accessor *args
    end
    args.each do |attr|
      class_eval do
        define_method(attr) do
          self.class.send(attr)
        end
      end
    end
  end
end

What above code does is, creates those class instance variables at class scope and also creates accessor methods for it, so that it doesn’t have to suck when used from class instances(remember @foo.class.i_am_class_instance_var)

class Foobar
  iattr_accessor :foo
end
Foobar.foo = "Hemant"
p Foobar.foo
lol = Foobar.new
p lol.foo

Did i miss anything? comments?

We hate reinventing the wheel. But when the wheel doesn’t exist, or is square, we’re not afraid to invent a round one.