Structured Design

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Rules of Thumb

1. One function per component or subcomponent.
2. Factor out each well-defined function performed by a component at the next level of abstraction.
3. Minimize duplication of code.
4. Limit "fan-out" (number of subcomponents for any given component to about 7.
   • 7 plus or minus 2 is the number of things humans can do or remember simultaneously.

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What Structure Charts Do NOT Show:

1. The order in which subcomponents are called.
2. Whether subcomponents are called once or repeatedly.
3. The internal workings of components.
4. The internal data used by components.

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Structured Design Overview | Structure Charts | Rules of Thumb

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Alyce Brady, Kalamazoo College