nonbuiltin

Nonbuiltin is an adjective used in computing to describe components, features, or entities that are not provided by the core built-in facilities of a programming language, runtime, or shell. Nonbuiltin include user-defined code, libraries, modules, plugins, and external tools. They contrast with builtins, which are always available as part of the standard environment.

In programming languages, nonbuiltin encompass functions and data types defined by programmers, as well as modules or packages imported from libraries. For example, in Python, user-defined functions and classes are nonbuiltin, as are modules such as numpy or requests; built-in functions include len and range. In shells, built-ins like cd and echo are treated differently from external commands such as grep or awk, which are nonbuiltins.

Access to nonbuiltin components typically requires explicit loading, importation, or installation. Mechanisms include import or require statements, module paths, package managers, or dynamic linking. This loading can affect portability and startup time and introduces dependency considerations.

From a design perspective, relying on nonbuiltin components supports modularity and extensibility but requires careful dependency management, version control, and compatibility checks. Documentation should clearly specify which nonbuiltins are required, their versions, and the environments in which they are available.

See also: built-in, library, module, extension, plugin, dependency management.