close

/*
 * call-seq:
 *   strio.close  -> nil
 *
 * Closes strio.  The *strio* is unavailable for any further data 
 * operations; an +IOError+ is raised if such an attempt is made.
 */
static VALUE
strio_close(self)
    VALUE self;
{
    struct StringIO *ptr = StringIO(self);
    if (CLOSED(ptr)) {
        rb_raise(rb_eIOError, "closed stream");
    }
    ptr->flags &= ~FMODE_READWRITE;
    return Qnil;
}