closed_write?

/*
 * call-seq:
 *   strio.closed_write?    -> true or false
 *
 * Returns +true+ if *strio* is not writable, +false+ otherwise.
 */
static VALUE
strio_closed_write(self)
    VALUE self;
{
    struct StringIO *ptr = StringIO(self);
    if (WRITABLE(ptr)) return Qfalse;
    return Qtrue;
}