Connie's Convenience Store - About Peter Coad

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24 Connie’s Convenience Store Applying Patterns: Select and Organize Problem-Domain Objects Session and the subsequent transactions Consider a session object. A session is a transaction. What are its subsequent transactions? In other words, what “event remembered,” what significant moment in time occurs after a session? What follows a session transaction? Hopefully, one or more sales. What follows a sale transaction? Hopefully, one or more payments. Connect the objects, using two instances of the transaction–subsequent transaction pattern (Figure 1–13): Container-content Session Sale Payment Figure 1–13: Session-sale and sale-payment. #14. “Container-Content” Pattern aggregate patterns number name capacity aboutMe n 1 n 1 Container howMany howMuch rankContents calcOverContents calcForMe n 1 Content number size weight dimensions aboutMe calcForMe rateMe • Typical object interactions howMany —> calcForMe calcOverContents —> calcForMe howMuch —> calcForMe rankContent —> rateMe • Examples Containers airport, aircraft, aisle, bank, bin, building, cabinet, folder, garage, hangar, hospital, locker, room, safe, store, warehouse. Container–content aircraft-cargo; aircraft-passenger; building-room; catalog–catalog item, storeitem; warehouse–loading dock. • Combinations container-content (again); container–container line item; group-member; assemblypart. Also, when “container” or “content” is a participant, place, or specific item: actor-participant; participant-transaction; place-transaction; specific item–transaction; specific line item–line item; item–specific item.
Applying Patterns: Select and Organize Problem-Domain Objects Connie’s Convenience Store 25 A store, as content Consider a store as content, then as a container. A store is a part of a chain. “Chain” would be interesting, especially if you wanted to do a calculation across a collection of stores. Not this time, however. A store, as a container A store is a domain-based container. Think of the store as a large container. What does it contain? Look inside. A store contains registers, items, cashiers (Figure 1–14). Store is a domain-based container. Domain-based containers are a convenient place for expressing responsibilities across a collection of other domain objects, ones that are not already taken care of by some other collection. Eventually, you may want add to the kinds of objects that a store object knows. Figure 1–14: Store–register, item, cashier. Note that a store object knows its registers, items, and cashiers. That makes sense. On notation: in each case, the triangle points from a part to a whole. Transaction–transaction line item A sale is a transaction. Nearly all transaction objects have corresponding transaction line items. Store n n Register Item Cashier n 1 1 1
Page 1 and 2: GETTING STARTED 1 Connie’s Conven
Page 3 and 4: Identifying System Purpose and Feat
Page 5 and 6: Selecting Objects Connie’s Conven
Page 7 and 8: Selecting Problem-Domain Objects Co
Page 19 and 20: Applying Patterns: Select and Organ
Page 23: Applying Patterns: Select and Organ
Page 29 and 30: Establishing Responsibilities for P
Page 55 and 56: Applying Patterns: Establish Proble
Page 61 and 62: Working Out Problem-Domain Dynamics
Page 63 and 64: Working Out Problem-Domain Dynamics
Page 65 and 66: Scenario: sale calculates its total
Page 67 and 68: Selecting Human-Interaction objects
Page 69 and 70: Establishing Human Interaction Resp
Page 71 and 72: Establishing Human Interaction Resp
Page 73 and 74: Working Out Human-Interaction Dynam
Page 75 and 76:
Scenario: actual cashier logs on. S
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Scenario: sell item. Receipt SaleLi
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Scenario: get payment by check Rece
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Selecting System-Interaction Object
Page 83 and 84:
Establishing System-Interaction Res
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Working Out System-Interaction Dyna
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Selecting Data-Management Objects a
Page 89 and 90:
Working Out Data-Management Dynamic
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Progress at This Point Connie’s C
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Progress at This Point Connie’s C
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Wrap Up Connie’s Convenience Stor
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