1. Lecture 6 Project review
Patterns: Shopper + Structural patterns (Neeraj)
Strategies: Design by Contract
Use case abuse/Objectory
Requirements for better design/programming languages
APPCs
OCL
11/13/2018
Lecture 6

2. APPC Consists of provided interface required interface implementation
methods to class-valued variables
output port to other components
required interface
methods from class-valued variables
interface to class graph: paths required
input ports from other components
implementation
11/13/2018
Lecture 6

3. APPC Required interface methods from class-valued variables
interface to class graph: paths required
A set of traversal strategies
defining a set of participants from a single source following unique paths
input ports from other components
11/13/2018
Lecture 6

4. APPC Implementation methods: refer to participants methods may call
next(): result from next component
next().n: result from used component n
subtraversal().s: continue traversal following strategy edge s
11/13/2018
Lecture 6

5. Kinds of APPCs Visitor style Adjuster style
single-traversal collaborations
Adjuster style
multi-traversal collaborations
11/13/2018
Lecture 6

6. Kinds of APPCs Visitor style single-traversal collaborations
single strategy parameter, uniform single method name backbone of collaboration
calls subtraversal().s // follow down strategy edge s
11/13/2018
Lecture 6

7. Kinds of APPCs Adjuster/Contract style multi-traversal collaborations
several strategy parameters
no calls to subtraversal().s
11/13/2018
Lecture 6

8. Role of strategy graph
At some class A we don’t call next() only subtraversal().x and subtraversal().y with any Java code in between.
Strategy graph describes where we might traverse: is the case anyway with around methods.
11/13/2018
Lecture 6

9. Shopper
Intent: A consumer object (shopper) obtains a collection of items from a provider object without introducing coupling between shopper and provider objects.
11/13/2018
Lecture 6

10. Shopper
Example
A set of collaborating application objects that implement the basic functionality
A set of report/view generator objects, each generating a report or view consisting of a collection of application information items
11/13/2018
Lecture 6

11. Consumer: Provider: Shopper Application objects Before traversal:
List {x,y,z}
Bag {}
A: x=2
B: y=7
F: z=9
After traversal:
List {x,y,z}
Bag {2,7,9}
11/13/2018
Lecture 6

12. Implementation A{ Bag shopper() { to *; Bag b = new B(); before * (@
does class have something in
shopping list: append host to
return b; }}
11/13/2018
Lecture 6

13. Implementation A{ Bag shopper() { to {A,B,F}; Bag b = new B();
before A
append host.get_x() to
...
return b; }}
11/13/2018
Lecture 6

14. Strategies
Definition
Implementation
11/13/2018
Lecture 6