Librarydefined

Librarydefined is an adjective used in software development to describe elements that are defined by a library rather than by the application code. In this sense, librarydefined components include data types, functions, classes, templates, macros, constants, and configuration objects that are provided as part of a library's interface or its internal implementation. They are designed to be reused across programs and are documented by the library authors.

Librarydefined elements contrast with userdefined components, which are created by developers using the library. The term is often used in API design, dependency management, and documentation to distinguish what is supplied by a platform or third-party library from what is authored by the application.

Examples include the standard library types in a programming language (such as list or math functions in Python's standard library) or a GUI toolkit's Widget classes. System libraries and external libraries fill predefined roles, enabling developers to build functionality without implementing these elements themselves.

Because librarydefined interfaces are maintained by library authors, they typically come with versioned guarantees. Upgrading a library may introduce breaking changes or deprecations, so developers must consult change logs and adapt code accordingly. Librarydefined elements may be subject to license and distribution constraints.

Designers of APIs strive to minimize breaking changes to librarydefined interfaces while evolving capabilities. Developers should prefer stable, well-documented librarydefined components for reliability, and clearly separate such definitions from application-specific code during maintenance and testing.