1. CRC Cards (class-responsibility-collaborator)

2. CRC 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
CRC Cards

3. CRC Card format
CRC Cards

4. CRC definitions
responsibility: knowledge class maintains or service class provides
collaborator: a class whose knowledge or services are needed to fulfill a responsibility
CRC Cards

5. 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
CRC Cards

6. 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
CRC Cards

7. 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
CRC Cards

8. Exercise
create CRC cards for a library
CRC Cards