checksextends

Checksextends is a term used in software engineering to describe a static analysis or enforcement mechanism that verifies inheritance relationships in source code. It focuses on ensuring that a class or type explicitly extends a designated base type according to the project's architectural rules, and that such extensions conform to the intended hierarchy.

The concept arises from the broader practice of enforcing architectural constraints through automated checks. In languages that use an explicit extends keyword or equivalent syntax, checksextends tools inspect the codebase to confirm that subclass declarations align with prescribed base classes or interfaces. The aim is to prevent deviations from the intended inheritance structure, which can affect behavior, maintainability, and dependencies.

Implementation of a checksextends rule typically involves parsing the source code to build an abstract syntax tree, locating class or type declarations, and comparing their base types against an allowed set or pattern. If a class extends an unauthorized base, or fails to extend a required base in a framework or library, the tool emits a warning or error. Such checks are commonly integrated into linters, compiler plugins, or continuous integration pipelines.

Common use cases include enforcing that domain model classes extend a common base, ensuring UI components derive from a standardized framework base, or preventing circumvention of design constraints in large teams. Checksextends complements other static checks by focusing specifically on inheritance structure rather than general code quality.

Limitations include handling dynamic inheritance or runtime manipulation, cross-language variances in how inheritance is expressed, and the potential for false positives in edge cases. It is thus typically used in conjunction with broader architectural and design reviews.

See also: inheritance, extends, static analysis, linting, architectural enforcement.