Rails tips

class Moo
  private

  def self.foo
    puts 'foo'
  end
end

Foo.foo
=> 'foo'

moo = Moo.new
moo.foo = 'foo'
moo.bar

moo = Moo.new.tap { |a| a.foo = 'foo'; a.bar }

class Moo
  attr_accessor :foo

  def initialize(&block)
    yield self if block_given?
  end

  def bar
    puts "bar!"
  end
end

moo = Moo.new do |a|
  a.foo = 'foo'
  a.bar
end

puts moo.foo

class Moo
  def initialize(&block)
    instance_eval &block if block_given?
  end

  def moo(val = nil)
    @moo = val unless val.nil?
    @moo
  end

  def bar
    puts "bar!"
  end
end

a = Moo.new do
  moo 'moo~!'
  bar
end

puts a.moo

class CreateDataVolumes < ActiveRecord::Migration
  def up
    Data::VOLUMES.times do |volume|
      create_table "data_#{volume}" do |t|
        # ...
      end
    end
  end
end

class CreateDataVolumes < ActiveRecord::Migration
  class Data < AR::Base
    VOLUMES
  end

  def up
    Data::VOLUMES.times do |volume|
      # ...
    end
  end
end