if (Options.sort_menus)

        if (Options.sort_menus != -1 &&
            (int)items_in_class.size() >= Options.sort_menus)

// read a value which can be either a boolean (in which case return
// 0 for true, -1 for false), or a string of the form PREFIX:NUMBER
// (e.g., auto:7), in which case return NUMBER as an int.
static int read_bool_or_number( const std::string &field, int def_value,
                                const std::string& num_prefix)
{
    int ret = def_value;
    if (field == "true" || field == "1" || field == "yes")
        ret = 0;
    if (field == "false" || field == "0" || field == "no")
        ret = -1;
    if ( field.find(num_prefix) == 0 )
        ret = atoi(field.c_str() + num_prefix.size());
    return (ret);
}

    sort_menus             = false;

    sort_menus             = 5;

        sort_menus = read_bool(field, sort_menus);

        sort_menus = read_bool_or_number(field, sort_menus, "auto:");

    bool        sort_menus;

    int        sort_menus;        // 0 = always, -1 = never, number = beyond
                                  // that size.

    { "sort_menus", &Options.sort_menus, option_hboolean },

sort_menus = false

sort_menus = auto:5

        equipment slot.

        equipment slot. When set to a number - using a syntax of the form
        sort_menus = auto:5 - items are sorted by their description if
        the total number of items in that category is at least that
        number; in the default case, having 4 kinds of potions would not
        sort them, but having 5 would.