Packaging provides a way of extending its commands by the use of pre- and post-command hooks. Hooks are Python functions (or any callable object) that take a command object as argument. They’re specified in config files using their fully qualified names. After a command is finalized (its options are processed), the pre-command hooks are executed, then the command itself is run, and finally the post-command hooks are executed.
See also global setup hooks in Specification of the setup.cfg file.
As a hook is configured with a Python dotted name, it must either be defined in a module installed on the system, or in a module present in the project directory, where the setup.cfg file lives:
# file: _setuphooks.py
def hook(install_cmd):
metadata = install_cmd.dist.metadata
print('Hooked while installing %r %s!' % (metadata['Name'],
metadata['Version']))
Then you need to configure it in setup.cfg:
[install_dist]
pre-hook.a = _setuphooks.hook
Packaging will add the project directory to sys.path and find the _setuphooks module.
Hooks defined in different config files (system-wide, user-wide and project-wide) do not override each other as long as they are specified with different aliases (additional names after the dot). The alias in the example above is a.