华师大面向对象程序设计-Lec12 设计类图及顺序图等1.ppt

Object oriented Analysis &Design面向对象分析与设计Lecture_08 GRASP
主讲: 陈小红
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Artifact Influences
Design
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Design
Supplementary Specs
Glossary
Data dictionary
Use Case under development, with System Sequence Diagram (System operations) and Contracts
Conceptual Model
Interactions, class diagram, etc
Packages
How?
OOD
After identifying your requirements and creating a domain model,
then add methods to the appropriate classes, and define the messaging between the objects to fulfill the requirements
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Requirement?
requirement
Use case/
SSD
SytemEvent/
OC
SystemEvent/
OC
Use case/…
SSD
Use case/
SSD
SystemEvent/
OC
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?
OO System
- objects collaborating to respond to System Events
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System
System Event
How to judge whether it is finished or not?
Operation Contract
Input /Output
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How to assign?
In the process
Refer to domain model
to assign task to objects and make them collaborating with each other
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How to evaluate whether it is a good design?
High cohesion
Low coupling
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Back to OODRealisation ways
The problem is
Above advice is too general to be handled
Deciding what methods belong to where and how objects should interact carries consequences and should be undertaken seriously
responsibility-driven design (RDD)
thinking about how to assign responsibilities to collaborating objects
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