B<Boolean>. Set this if the attribute must be passed on instantiation.
+=item * reader
+
+The value of this attribute will be the name of the method to get the value of
+the attribute. If you like Java style methods, you might set this to
+C<get_foo>
+
+=item * writer
+
+The value of this attribute will be the name of the method to set the value of
+the attribute. If you like Java style methods, you might set this to
+C<set_foo>
+
=item * weak_ref
B<Boolean>. Set this if you want the reference that the attribute contains to