最病 O The designer's motto n Ask not first What the system does Ask What it does it to! Institute of Computer Software 2021/1/28 Nanjing University
The designer’s motto Ask NOT first WHAT the system does: Ask WHAT it does it TO! 2021/1/28 Institute of Computer Software Nanjing University 16
面向对象设计的相关问题 n How to find the object types? n How to describe the object types a How to describe the relations and commonalities between object types n How to use object types to structure programs Institute of Computer Software 2021/1/28 Nanjing University
面向对象设计的相关问题 How to find the object types? How to describe the object types? How to describe the relations and commonalities between object types? How to use object types to structure programs? 2021/1/28 Institute of Computer Software Nanjing University 17
对象刻画 a Consider not a single object but a type of objects with similar properties. a Define each type of objects not by the objects physical representation but by their behavior: the services FEATURES)they offer to the rest of the world a External, not internal view: ABSTRACT DATA TYPES Institute of Computer Software 2021/1/28 Nanjing University
对象刻画 Consider not a single object but a type of objects with similar properties. Define each type of objects not by the objects’ physical representation but by their behavior: the services (FEATURES) they offer to the rest of the world. External, not internal view: ABSTRACT DATA TYPES 2021/1/28 Institute of Computer Software Nanjing University 18
对象刻画问题 o The main issue: How to describe program objects (data structures) a Completely a Unambiguously a Without overspecifying? (Remember information hiding Institute of Computer Software 2021/1/28 Nanjing University
对象刻画问题 The main issue: How to describe program objects (data structures)? Completely Unambiguously Without overspecifying? ◼ (Remember information hiding) 2021/1/28 Institute of Computer Software Nanjing University 19