dependson

Dependson is a term used in software engineering to describe a relationship in which one component requires another to function, be built, or be installed. The concept underpins many areas, including build systems, packaging, and task orchestration. In practice, dependson establishes a directed acyclic graph where edges point from dependents to dependencies; enforcing an ordering so that prerequisites are satisfied before dependents proceed.

In build systems, a target often lists prerequisites. For example, in Make, a target file is built from prerequisites; the rule ensures that the dependent builds only after its dependencies are up to date. In more explicit DSLs, Gradle uses Task.dependsOn to declare that one task should run before another. CMake uses add_dependencies to enforce build order between targets.

In packaging and distribution, dependson corresponds to runtime or build-time dependencies. Debian and derivatives declare runtime dependencies in control files with a Depends field, e.g., Depends: libfoo (>= 1.2). The packaging system ensures those packages are installed before the software is installed or run.

In Homebrew, formulae specify dependencies with depends_on, for example depends_on "[email protected]". Other ecosystems may use camelCase names like dependsOn in Gradle or similar attributes in deployment pipelines to express that one step or job depends on another.

Common considerations include handling optional or conditional dependencies, version constraints, and the possibility of circular dependencies, which are typically rejected or warned about by tooling.

While the exact syntax varies by tool, the core idea of dependson remains the same: defining explicit dependencies to ensure correct build, install, and run-time behavior.