Lazy-lize class loading dependency

gistfile1.rb

# bad
class Book
  belongs_to :categoy, :class_name => BookCategory
end

# good
class Book
  belongs_to :categoy, :class_name => 'BookCategory'
end

# bad
class Institution
  STRATEGY = SomeStrategy

  def strategy
    STRATEGY    
  end
end

# good
class Institution
  STRATEGY = 'SomeStrategy'

  def strategy
    STRATEGY.constantize
  end
end

# bad
class Book
  scope :for_children, where(category_id: Category::CHILDRED_CATEGORY_IDS)
end

# good
class Book
  scope :for_children, lambda {
    where(category_id: Category::CHILDREN_CATEGORY_IDS)
  }
end