Connie's Convenience Store - About Peter Coad

Establishing Responsibilities for Problem-Domain Objects Connie’s Convenience Store 37
More importantly, a store object gives you a place to put those calculations that
apply across a collection of what a store contains: registers, items, and cashiers.
#102. “Service across a Collection” Strategy establishing responsibilities /
what I do (where to put)
• Service across a collection of objects?
Add a service to a collection object, an object that knows and does things across that
collection.
Let each worker within a collection do its fair share—as much as it can, based upon
what it knows.
• Be sure the collection does just those things that apply across a collection; makes its
workers do as much work as they know enough to accomplish.
• Across its workers: enforce business rules that may apply to its participation.
Establish responsibilities: “what I know.”
#53. “Establish Place Attributes” Strategy establishing responsibilities /
what I know (pattern players)
• For location, include: number, name, address (perhaps latitude, longitude, altitude).
Just include the name of the store; that’s enough for now.
– name.
Establish responsibilities: “who I know.”
#75. “Establish Place Object establishing responsibilities /
Connections” Strategy who I know (pattern players)
• For a location, include object connections to objects which come to rest at a location . . .
or are contained by a location.
• For a location, include object connections to transaction objects, to show that location’s
participation in that transaction.
Who does a store object know? A store object, as a container, knows its contents:
– registers (zero or more)
– items (zero or more)
– cashiers (zero or more).