Guardtypes

Guardtypes is a conceptual taxonomy used in software engineering to describe the various guards that protect code, data, and state from invalid inputs or unauthorized actions. The term is not universal, but it is used in some discussions of software design to organize guard logic into distinct categories such as input validation, state invariants, and access controls.

Common guardtypes include precondition guards, which check inputs before a function runs; postcondition guards, which validate results or state after execution; type guards, which verify that a value conforms to an expected type at runtime; security guards, which enforce authentication and authorization checks; and resource guards, which ensure resources are allocated and released safely.

In practice, guardtypes help separate concerns and improve maintainability by grouping related checks. In languages with guard clauses or pattern matching, guardtypes can be expressed as distinct conditional expressions that refine control flow. In security architectures, guardtypes map to different layers of defense, and in systems engineering, they support runtime verification and contract-based design.

See also: design by contract, guard clause, pattern matching, access control, runtime verification.