Connie's Convenience Store - About Peter Coad

26 Connie’s Convenience Store Applying Patterns: Select and Organize Problem-Domain Objects
#6. “Transaction–Transaction Line Item” Pattern transaction patterns
Transaction
number
date
time
status
aboutMe
howMany
howMuch
rankLineItems
calcOverLineItems
calcForMe
• Typical object interactions
howManyOverInterval —> calcForMe calcOverLineItems —> calcForMe
howMuchOverInterval —> calcForMe rankLineItems —> rateMe
• Examples
Transaction: agreement, assignment, authorization, contract, delivery, deposit,
incident, inquiry, order, payment, problem, report, purchase, refund, registration,
rental, reservation, sale, shift, shipment, subscription, time charge, title,
withdrawal.
Transaction–transaction line item: deposit–deposit line item; order–order line item;
payment–payment line item; rental–rental line item; sale–sale line item;
shipment–shipment line item; withdrawal–withdrawal line item.
• Combinations
participant-transaction; place-transaction; specific item–transaction;
transaction–subsequent transaction; transaction line item–subsequent transaction
line item; item–line item; specific item–line item.
Connect a sale and its parts, sale line items, in your model (Figure 1–15):
Figure 1–15: Sale-sale line item.
Note that a sale object knows one or more sale line item objects.
Sale
1-n
1
SaleLineItem
1-n 1
TransactionLineItem
number
date
time
status
aboutMe
calcForMe
rateMe