def initialize(dllname, func, import, export = "0", calltype = :stdcall)
  @proto = [import].join.tr(WIN32_TYPES, DL_TYPES).sub(/^(.)0*$/, '\1')
  import = @proto.chars.map {|win_type| TYPEMAP[win_type.tr(WIN32_TYPES, DL_TYPES)]}
  export = TYPEMAP[export.tr(WIN32_TYPES, DL_TYPES)]
  calltype = Fiddle::Importer.const_get(:CALL_TYPE_TO_ABI)[calltype]
  handle = DLL[dllname] ||=
           begin
             Fiddle.dlopen(dllname)
           rescue Fiddle::DLError
             raise unless File.extname(dllname).empty?
             Fiddle.dlopen(dllname + ".dll")
           end
  @func = Fiddle::Function.new(handle[func], import, export, calltype)
rescue Fiddle::DLError => e
  raise LoadError, e.message, e.backtrace
end