RDD Master
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- Responsibility-Driven Design
- Responsibility implies Non-Interference
- Works better for programming-in-the-large vs. programming-in-the-small
- Where software is built by team and responsibility must be shared
- Where the management of details and COMMUNICATION are the main problems
- Tasks in RDD
- Work through scenarios
- Identify components
- Components have a small well-defined set of responsibilities
- Components should interact with other components to the minimal extent possible
- CRC Cards-Recording Responsibility
- Component, Responsibility, Collaborator (CRC) Cards
- Use a specific scenario to flesh out the CRC cards
- In-class Activity: Try it with a problem (Rolodex? Adventure games?)
- Why CRC Cards?
- Give Components a Physical Representation
- The What/Who Cycle
- Documentation for those who come after
- Goals in Specifying Components and Behavior
- Postpone Decisions
- Don't become "design-fixated"
- Don't make important decisions early
- Prepare for Change
- Primary objective: Changes should affect as few components as possible
- Try to predict likely sources of change and isolate those
- Try to isolate and reduce hardware dependencies
- Reduce coupling
- Record major decisions
- Interaction Diagrams
- Replacement for "I am..." Notation
- Coupling and Cohesion
- Cohesion is the degree to which the responsibilities of a single component form a meaningful unit
- Coupling describes the relationship between software components
- Goal: Reduce coupling, increase cohesion
- Parnas' Principles: Interface and Implementation
- Separate them
- The developer of a software component must provide the intended user with all the information needed to make effective use of the services provided by the component, and should provide no other information
- The developer of a software component must be provided with all the information necessary to carry out the given responsibilities assigned to the component, and should be provided with no other information
- That's what O-O is all about
- Reduce coupling and increase cohesion
- Separate interface and implementation
- Put off design decisions, by...
- Doing analysis first
- Being as language-independent as possible
- Coad (and Yourdon) notation
- CRC cards
- "I am..." notation
- Event interaction diagrams
- Others:
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Last modified at 8/13/97; 4:49:25 PM
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