1. 1 © Wolfgang Pelz 2000-04CRC Cards CRC Cards (class-responsibility-collaborator)

2. 2 © Wolfgang Pelz 2000-04CRC Cards introduced in 1989 by Kent Beck and Ward Cunningham designed to teach object oriented programming at Tektronix a CRC card is an index card in a group setting used to represent: –a class of objects –their behavior –their interactions

3. 3 © Wolfgang Pelz 2000-04CRC Cards CRC Card format

4. 4 © Wolfgang Pelz 2000-04CRC Cards CRC definitions responsibility: knowledge class maintains or service class provides collaborator: a class whose knowledge or services are needed to fulfill a responsibility

5. 5 © Wolfgang Pelz 2000-04CRC Cards Methodology involves a creative exchange: –physical simulation of the workings of the system –participants become one or more objects during walk-throughs of typical scenarios –classes are discovered and converted into cards –responsibilities are assigned –collaborators for each responsibility are identified

6. 6 © Wolfgang Pelz 2000-04CRC Cards Advantages portable: cards can be used anywhere, even away from the computer or office anthropomorphic: no computer program can capture the essence of the interactions forced by passing the cards level of involvement felt by each team member increases useful throughout the life cycle

7. 7 © Wolfgang Pelz 2000-04CRC Cards More advantages provides a basis for more formal analysis and design methodologies serves as input to a formal method (i.e., a starting point) ease the transition from process orientation to object orientation - most formal methods are overwhelming gives a general bound on the size of a class - a card

8. 8 © Wolfgang Pelz 2000-04CRC Cards Exercise create CRC cards for some classes in your project.