Question on inheritance & association, pls help..

[krislioe]

Hi all,

I have two classes SalesOrder dan Invoice. The business rule is :
SalesOrder is processed/approved to produced an invoice.

So there is association between SalesOrder and Invoice.

On the other hand, Invoice has all the attributes that the SalesOrder
has EXCEPT for one attribute. (on example below : priority)

SalesOrder : docid, docno, docdate, customer, salesman,warehouse,
priority
Invoice : docid, docno, docdate, customer, salesman,warehouse,
DeliveryDate, LoadingDate, ReceiveDate, Amount

1) Should I create Invoice as subclass of SalesOrder ?

2) If the answer is yes, can we have both Extend and Association on the
relation of two entities like SalesOrder and Invoice ?

Thank you for your help,
xtanto

 

[Chris Brat]

Sounds like homework but anyway...

I'd rather have an abstract SalesDocument class that is extended by the
other two.

Have all the common fields and business logic in the SalesDocument
class and then have the Invoice and SalesOrder specific stuff in its
appropriate class.

You might only have one field that currently differs between SalesOrder
and Invoice but that can easily change - and you can add 'document'
specific methods where needed.

Chris