: new(dbname[, mode[, flags]])
: open(dbname[, mode[, flags]])
: open(dbname[, mode[, flags]]) {|db| ...}
    dbnameǻꤷǡ١⡼ɤ
    modeꤷƥץ󤷤ޤmodeξ
    άͤ0666ǤmodeȤnil
    ȥǡ١¸ߤʤˤϿʥǡ١餺
    nil֤ޤ

    flags ˤϡGDBM::FAST, GDBM::SYNC, GDBM::NOLOCK 
    ¤ꤷޤǥեͤϻʤ(Ĥޤ0)Ǥ

    ֥åꤷ硤ץ󤷤GDBM֥Ȥ
    ˥֥å¹Ԥޤ¹ԸGDBM֥Ȥ򥯥
    open᥽åɤϥ֥åη̤֤ޤϤ礦
    ʲƱǤ

      dbm = GDBM.open(file)
      begin
        yield dbm
      ensure
        dbm.close
      end

