class Teacher

  # This is NOT fine, because it's run at the loading of the class and captures Date.current and stores it in state.
  # If you're caching classes in Rails, this can be static for N number of days that it's kept in cache.
  named_scope :todays, :conditions => ['(due_date >= ?) & (due_date < ?)', Date.current, Date.tomorrow]

  # This is ok, because lambda guarantees that it's run at run time during the call.
  named_scope :todays, lambda{{:conditions => ['(due_date >= ?) & (due_date < ?)', Date.current, Date.tomorrow]}}

  # This is fine because it's not a cached thing and it's an instance method
  def find_todays
     Assigment.find(:all, :conditions => ['(due_date >= ?) & (due_date < ?)', Date.current, Date.tomorrow])
  end
end