pkgutil

pkgutil is a module in Python's standard library that provides utilities related to the import system and package discovery. It offers helpers for inspecting packages, finding modules, and accessing package resources. It is used by tooling that analyzes package contents, discovers modules, and supports certain types of namespace packaging.

The module's core capabilities include utilities for module discovery. The iter_modules(path=None, prefix='') function yields information about modules and packages found on a given path, returning ModuleInfo objects that describe the module finder, the name, and whether the entry is a package. The walk_packages(path=None, prefix='', onerror=None) function recursively yields ModuleInfo for all modules available on a path, enabling deeper inspection of a package’s contents without importing them.

In addition to discovery, pkgutil provides access to resources inside packages. The get_data(package, resource) function returns the contents of a resource file as bytes, which is useful for reading data files bundled with a package. The get_resource_reader(package) function returns a resource reader object when supported by the loader, facilitating more advanced resource access patterns.

Other utilities related to import and packaging include get_loader(fullname), which returns a loader object for a module if available, and get_importer(path), which returns a path entry finder for a given path entry. The extend_path(path, name) function is used to support namespace packages by extending a package’s __path__ with additional directories.

Overall, pkgutil provides lightweight tools for exploring package structures and accessing embedded resources, often serving as a compatibility layer between older import mechanisms and newer APIs. Some functionality is nuanced by changes in import systems over Python versions, so modern code may prefer importlib APIs for newer use cases.