Includer

An includer is a term used in computing and document processing to describe a component, tool, or module that inserts content from one source into another. It functions as part of a system that combines multiple files, templates, or data sources into a single output by resolving and embedding the referenced content.

Typical responsibilities of an includer include locating the target content, resolving file paths or resource identifiers, and merging the included material with the host document or program. It may support relative and absolute paths, search path configurations, and handling of include guards or guards against circular dependencies to prevent infinite recursion. Some includers apply transformations, such as macro expansion, variable substitution, or content filtering, during the inclusion process. Caching and deduplication are common optimizations to improve performance.

In practice, includers appear in various domains. In programming languages, preprocessor directives such as include or import commands act as includers by injecting header files or modules into source code. In web development and templating, include directives or partials allow templates to reuse snippets of HTML or other content. Documentation systems and static site generators frequently implement includers to assemble documents from modular components. Build and configuration tools may use includers to combine configuration fragments or build rules from separate files.

Security and correctness considerations are important for includers, including protecting against path traversal, validating sources, and handling untrusted content. While the term inclusor is sometimes used interchangeably with includer, the focus remains on correctly resolving and integrating external content into a target artifact. The concept is etymologically rooted in the act of including.