/*
 *  call-seq:
 *     FuzzyQuery.default_prefix_length = prefix_length -> prefix_length
 *
 *  Set the default value for +:prefix_length+
 */
static VALUE
frt_fq_set_dpl(VALUE self, VALUE val)
{
    int pre_len = FIX2INT(val);
    if (pre_len < 0) {
        rb_raise(rb_eArgError,
                 "%d < 0. :prefix_length must be >= 0", pre_len);
    }
    qp_default_fuzzy_pre_len = pre_len;
    rb_cvar_set(cFuzzyQuery, id_default_prefix_length, val, Qfalse);
    return val;
}