function res = length(this);

    tmp = struct(this);

    %if any(cellfun(@length, { tmp.EEG }) > 1)

    %    error('EEG structure in object with more than 1 element')

    %end

    try

        res = length(tmp.EEG);

    catch

        res = length(tmp);

        return;

    end

    if res > 1, error('EEG structure in object with more than 1 element'); end

    res = length(tmp);