6.8.3 Reusability measures

What this heading covers

Reuse is an outcome, not a property of a library. The measure can count assets reused in another context, the effort saved, or the proportion of a new product built from existing assets. A catalogue of components with no consumers measures nothing. The context matters: an asset reused inside the same product is not the same as one reused by another team, and the draft's family is about the product quality property, so the measure should be specific about the boundary.

Record position: family 28 of 40 in clause 6, under 6.8 Maintainability, which carries 5 families. It is one of the 40 families a programme has to map its measures to, and its elements are listed below. The heading is 6.8.3 in the public contents; the text behind it is not public.

How a measure for this family is built

Count the assets reused outside their original product or team as the numerator over the assets offered for reuse. For effort, compare the cost of the reused path with the estimated cost of building it. Record the reuse context and the consumer, because a copy is not a reuse.

What to put in place before publication

1. Define reuse as use by another consumer, not as a copy.
2. Record the version consumed, because reuse of an old version is a different result.

Evidence to keep

Two questions to ask

• Who reused the asset, in which product, at which version?
• Was the effort saving measured, or only the catalogue size?

Where teams usually fall short

• A component library counted as reuse because it exists.

What the number cannot tell you

It cannot tell you whether the reuse saved money. A reused asset that needed adaptation can cost more than a new one.

What happens next

Analysability is the next family and it decides how expensive the next change will be.