Software reuse greatly increase productivity and enhance quality in software development. The extraction of reusable software components from existing systems is critical to effective software reuse. Software reuse is classified into black-box reuse and white-box reuse. In white-box reuse, modifiability is the most important quality. If modification cost is greater than production cost then there is no need to reuse with modification. High understandability and low ripple-effect between software components are essential for increasing modifiability. In black-box reuse, however, information-hiding is the most important quality. The better the information-hiding, the better the black-box reuse, because we may not know the implementation details of every software components. We propose a new model for measuring of black-box reusability and white-box reusability. Also the factors of the model, and the measurement criteria are proposed. The validity of our model is shown through a case study using our model.
