to_str

static VALUE
name_err_mesg_to_str(VALUE obj)
{
    VALUE *ptr, mesg;
    TypedData_Get_Struct(obj, VALUE, &name_err_mesg_data_type, ptr);

    mesg = ptr[0];
    if (NIL_P(mesg)) return Qnil;
    else {
        const char *desc = 0;
        VALUE d = 0, args[NAME_ERR_MESG_COUNT];
        int state = 0;

        obj = ptr[1];
        switch (obj) {
          case Qnil:
            desc = "nil";
            break;
          case Qtrue:
            desc = "true";
            break;
          case Qfalse:
            desc = "false";
            break;
          default:
            d = rb_protect(rb_inspect, obj, &state);
            if (state)
                rb_set_errinfo(Qnil);
            if (NIL_P(d) || RSTRING_LEN(d) > 65) {
                d = rb_any_to_s(obj);
            }
            desc = RSTRING_PTR(d);
            break;
        }
        if (desc && desc[0] != '#') {
            d = d ? rb_str_dup(d) : rb_str_new2(desc);
            rb_str_cat2(d, ":");
            rb_str_append(d, rb_class_name(CLASS_OF(obj)));
        }
        args[0] = mesg;
        args[1] = ptr[2];
        args[2] = d;
        mesg = rb_f_sprintf(NAME_ERR_MESG_COUNT, args);
    }
    return mesg;
}