sitepath 0.4.0

the anti-packaging system

sitepath - the anti-packaging system

When making an importable Python library, there needs to be a middle ground between:

1. writing some code, and
2. building a package that can publish to PyPI.

Your code's directory is a package already. No extra packaging is required.

Using sitepath along with pip can allow locally developed code to coexist with PyPI-available libraries.

Examples

The directory my_project has your Python code. Let's make it importable, work within virtual environments, and not need setup.py or pyproject.toml.

python -m sitepath symlink ./my_project

Done. It symlinked the directory to a user-writable site-packages directory.

If you don't want it importable anymore:

python -m sitepath unsymlink my_project

Done.

On Windows, you might get an error because symlinks are not supported unless you have special permissions. Instead, you can use:

python -m sitepath copy ./my_project

This creates a separate copy of your code in a user-writable site-packages directory.

If you want to remove it:

python -m sitepath uncopy my_project

If you like the using python setup.py develop or editable installs with pip install -e for development:

python -m sitepath develop ./my_project

This will add the given project path to my_project.sitepath.pth in a user-writeable site-packages directory.

If you want to stop developing:

python -m sitepath undevelop my_project

which will remove its .pth file from site-packages.

Installing

The sitepath anti-packaging system can bootstrap itself (assuming you have sitepath/ in your current working directory).

python -m sitepath copy sitepath

But if you really want it from PyPI:

pip install sitepath

Useful Features

Calling python -m sitepath prints out useful information about your Python (virtual) environment:

• relevant environment variables
• sys.executable
• sys.path
• user site-packages path
• active site-packages
• active .pth files
• sitepath symlinks/copies/develops

------------------------------------------------------------
sitepath
------------------------------------------------------------

VIRTUAL_ENV=/home/serwy/venv-py/iso
sys.executable = '/home/serwy/venv-py/iso/bin/python'
sys.path = [
    '/home/serwy',
    '/usr/lib/python310.zip',
    '/usr/lib/python3.10',
    '/usr/lib/python3.10/lib-dynload',
    '/home/serwy/venv-py/iso/lib/python3.10/site-packages',
]
USER_SITE: '/home/serwy/.local/lib/python3.10/site-packages' (exists)
ENABLE_USER_SITE: False

Active site-packages:
    /home/serwy/venv-py/iso/lib/python3.10/site-packages

Active .pth files:
    /home/serwy/venv-py/iso/lib/python3.10/site-packages/distutils-precedence.pth

sitepath-symlinked packages: 1 found
    /home/serwy/venv-py/iso/lib/python3.10/site-packages/sitepath --> /home/serwy/gitea/my-sitepath/sitepath
sitepath-copied packages:    0 found
sitepath-developed packages: 0 found

Available Commands

To see the list of commands:

python -m sitepath help

They are:

• symlink [directory]
• unsymlink [name]
• copy [directory]
• uncopy [name]
• develop [directory]
• undevelop [name]
• info [names/directories]
• list [symlinks, copies, develops]
• mvp [name]
• help

Batch Processing

The -r <file> argument can be used to batch process a list of directories in a file and works for almost all commands. Blank lines and comment lines starting with # are ignored.

The list of linked/copied/developed packages can be saved:

python -m sitepath list copies > sitepath-copies.txt

and then re-loaded in a different virtual environment:

python -m sitepath copy -r sitepath-copies.txt

To uncopy the packages:

python -m sitepath uncopy -r sitepath-copies.txt

For the un* commands, -r requires that the path from the provided file matches the existing state found in the crumb, otherwise a mismatch failure occurs.

Using -nr will use the package name implied by each directory/file path and batches that instead. This ignores mismatched directory errors that may occur when using unlink/uncopy/undevelop.

Minimum Viable Packaging

If you want to have an initial pyproject.toml, use the mvp command and redirect its output:

python -m sitepath mvp my_project > pyproject.toml

This pyproject.toml file should NOT be used to distribute the project on PyPI. It's missing many fields that should be completed first.

Commentary

Develop and .pth files

The preferred method is to use symlink instead of develop, if your platform permits it.

The develop command takes its name from the setuptools interface. It works by adding the parent directory containing your code to sys.path. On Python startup, the site module finds site-packages/*.pth files, which includes easy-install.pth populated by setuptool's develop command.

The downside of using develop (from setup.py and from sitepath) is that everything in the path is potentially top-level importable. This is a consequence of using .pth files.

Modifying site-packages

Commands that modify a site-packages directory leave a [package].sitepath crumb file for each package it copies/links, and this crumb is needed to modify or remove an existing package. This crumb distinguishes sitepath packages from everything else.

Building, Packaging and Distribution

Using sitepath removes the need of dealing with the tedious minutia of PyPA packaging requirements from early development stages. In time, more packaging may be needed, or sitepath may be adequate for your needs, especially for internally developed code without an internal package repository.

Symbolic Links

Unix, Linux, and MacOS have had symbolic links for decades, available without needing special privileges. While Windows has support for symbolic links, using them requires privileged permissions because of the implications of that platform's legacy design choices.

See Also:

• Standard Library:
  • https://docs.python.org/3/library/site.html
• Packaging:
  • https://packaging.python.org/en/latest/tutorials/packaging-projects/
  • https://docs.python.org/3/distributing/index.html#publishing-python-packages
  • https://packaging.python.org/en/latest/guides/tool-recommendations/#packaging-tool-recommendations
• Symlinks on Windows:
  • https://learn.microsoft.com/en-us/windows/security/threat-protection/security-policy-settings/create-symbolic-links
  • https://docs.python.org/3/library/os.html#os.symlink