requiredby

RequiredBy is a term used in dependency graphs, build systems, and software architecture to describe which components depend on a given component. It represents the set of dependents for a particular item. Formally, if component B requires component A to function, then B is included in the RequiredBy set of A. The relation is the inverse of the Requires (or depends-on) relation found in many models.

The concept is useful for impact analysis, change management, and maintenance. Knowing who is RequiredBy a component helps teams estimate the potential effects of altering or removing that component. It also supports optimization and visualization tasks by showing how changes propagate through a system.

In practice, RequiredBy can be determined by examining the dependency graph and reversing the direction of edges: for each edge indicating that B depends on A, A gains B in its RequiredBy collection. In graph databases and build tools, specific queries or operations fetch all items that reference a given component as a dependency.

Example: if library L is used by applications X and Y, then L’s RequiredBy set is {X, Y}. Conversely, X and Y have Requires relationships pointing to L (and possibly other components).

Considerations include the possibility of cyclic dependencies, which can complicate the interpretation of RequiredBy. The meaning and availability of the RequiredBy information depend on the domain and the data model, but the core idea remains: RequiredBy identifies all elements that rely on a given item. See also Requires, Dependency, Dependency graph, and Impact analysis.