class CFPropertyList::CFDate

def initialize(value = nil,format=CFDate::TIMESTAMP_UNIX)

set value to defined state 
def initialize(value = nil,format=CFDate::TIMESTAMP_UNIX)
  if(value.is_a?(Time) || value.nil?) then
    @value = value.nil? ? Time.now : value
  else
    set_value(value,format)
  end
end