Packagedata

Packagedata refers to the mechanism by which non-code files are declared to be included inside a software package distribution. It is commonly used in software packaging to ensure that data files such as images, templates, configuration files, or other resources travel with the installed package, rather than being omitted during packaging.

In Python packaging with setuptools, the term is typically realized through the package_data argument of the setup function. The value is a dictionary that maps package names to lists of glob patterns describing the files to include inside that package. For example: package_data={'mypkg': ['data/*.dat', 'templates/*.html']}. These paths are relative to the respective package directory. The goal is to have the listed files copied into the installed package (for example, into the site-packages/mypkg directory) when building wheels or sdist distributions.

Packagedata works in concert with other packaging options. The include_package_data flag and MANIFEST.in control files included in source distributions, while package_data specifies files to ship with the package itself. It is important to distinguish: package_data explicitly enumerates files inside packages, whereas MANIFEST.in can declare additional files to include in source distributions. Using both options correctly ensures data files appear in both source distributions and installed environments.

Common considerations include ensuring the patterns match files within the package, understanding that some environments may treat data files differently (for example, with respect to packaging or runtime access), and avoiding accidental inclusion of build artifacts. Properly declared packagedata helps maintain consistent behavior across development, distribution, and deployment.