Safe file opening

    procedure open_file  (the_file : in out FILE_TYPE) is 

        filename : string (1..30);
        namelen  : natural;

    begin

        PUT ("What file do you want to read? ");
        GET_LINE (filename, namelen);
        OPEN (FILE => the_file,
              NAME => filename(1..namelen),
              MODE => IN_FILE);

    exception

        when STATUS_ERROR =>
            PUT_LINE ("The file is already open");
        when NAME_ERROR =>
            PUT_LINE ("There is no file with that name");
        when USE_ERROR =>
            PUT_LINE ("The file cannot be read");
        when others =>
            PUT_LINE ("Unexpected error on opening file");

    end open_file;