--- autoload(const_name, feature)

     const_name ǽ˻Ȥ feature 
    require 褦ꤷޤconst_name
    ʸޤ Symbol ǻꤷޤ
    ʤconst_name ˤϡ"::" 黻Ҥޤ뤳ȤϤǤޤ
    (Ĥޤꡢȥåץ٥Ǥޤ)

    nil ֤ޤ

