diff --git a/source/discussions/src-layout-vs-flat-layout.rst b/source/discussions/src-layout-vs-flat-layout.rst index bfa405729..c38968345 100644 --- a/source/discussions/src-layout-vs-flat-layout.rst +++ b/source/discussions/src-layout-vs-flat-layout.rst @@ -79,3 +79,27 @@ layout and the flat layout: ``tox.ini``) and packaging/tooling configuration files (eg: ``setup.py``, ``noxfile.py``) on the import path. This would make certain imports work in editable installations but not regular installations. + +.. _running-cli-from-source-src-layout: + +Running a command-line interface from source with src-layout +============================================================ + +Due to the firstly mentioned specialty of the src layout, a command-line +interface can not be run directly from the :term:`source tree `, +but requires installation of the package in +:doc:`Development Mode ` +for testing purposes. Since this can be unpractical in some situations, +a workaround could be to prepend the package folder to Python's +:py:data:`sys.path` when called via its :file:`__main__.py` file: + +.. code-block:: python + + import os + import sys + + if not __package__: + # Make CLI runnable from source tree with + # python src/package + package_source_path = os.path.dirname(os.path.dirname(__file__)) + sys.path.insert(0, package_source_path) diff --git a/source/guides/analyzing-pypi-package-downloads.rst b/source/guides/analyzing-pypi-package-downloads.rst index 62efea7ab..5fecc99c1 100644 --- a/source/guides/analyzing-pypi-package-downloads.rst +++ b/source/guides/analyzing-pypi-package-downloads.rst @@ -1,3 +1,5 @@ +.. _analyzing-pypi-package-downloads: + ================================ Analyzing PyPI package downloads ================================ diff --git a/source/guides/creating-command-line-tools.rst b/source/guides/creating-command-line-tools.rst new file mode 100644 index 000000000..9f040ce7d --- /dev/null +++ b/source/guides/creating-command-line-tools.rst @@ -0,0 +1,192 @@ +.. _creating-command-line-tools: + +========================================= +Creating and packaging command-line tools +========================================= + +This guide will walk you through creating and packaging a standalone command-line application +that can be installed with :ref:`pipx`, a tool creating and managing :term:`Python Virtual Environments ` +and exposing the executable scripts of packages (and available manual pages) for use on the command-line. + +Creating the package +==================== + +First of all, create a source tree for the :term:`project `. For the sake of an example, we'll +build a simple tool outputting a greeting (a string) for a person based on arguments given on the command-line. + +.. todo:: Advise on the optimal structure of a Python package in another guide or discussion and link to it here. + +This project will adhere to :ref:`src-layout ` and in the end be alike this file tree, +with the top-level folder and package name ``greetings``: + +:: + + . + ├── pyproject.toml + └── src + └── greetings + ├── cli.py + ├── greet.py + ├── __init__.py + └── __main__.py + +The actual code responsible for the tool's functionality will be stored in the file :file:`greet.py`, +named after the main module: + +.. code-block:: python + + import typer + from typing_extensions import Annotated + + + def greet( + name: Annotated[str, typer.Argument(help="The (last, if --gender is given) name of the person to greet")] = "", + gender: Annotated[str, typer.Option(help="The gender of the person to greet")] = "", + knight: Annotated[bool, typer.Option(help="Whether the person is a knight")] = False, + count: Annotated[int, typer.Option(help="Number of times to greet the person")] = 1 + ): + greeting = "Greetings, dear " + masculine = gender == "masculine" + feminine = gender == "feminine" + if gender or knight: + salutation = "" + if knight: + salutation = "Sir " + elif masculine: + salutation = "Mr. " + elif feminine: + salutation = "Ms. " + greeting += salutation + if name: + greeting += f"{name}!" + else: + pronoun = "her" if feminine else "his" if masculine or knight else "its" + greeting += f"what's-{pronoun}-name" + else: + if name: + greeting += f"{name}!" + elif not gender: + greeting += "friend!" + for i in range(0, count): + print(greeting) + +The above function receives several keyword arguments that determine how the greeting to output is constructed. +Now, construct the command-line interface to provision it with the same, which is done +in :file:`cli.py`: + +.. code-block:: python + + import typer + + from .hello import greet + + + app = typer.Typer() + app.command()(greet) + + + if __name__ == "__main__": + app() + +The command-line interface is built with typer_, an easy-to-use CLI parser based on Python type hints. It provides +auto-completion and nicely styled command-line help out of the box. Another option would be :py:mod:`argparse`, +a command-line parser which is included in Python's standard library. It is sufficient for most needs, but requires +a lot of code, usually in ``cli.py``, to function properly. Alternatively, docopt_ makes it possible to create CLI +interfaces based solely on docstrings; advanced users are encouraged to make use of click_ (on which ``typer`` is based). + +Now, add an empty :file:`__init__.py` file, to define the project as a regular :term:`import package `. + +The file :file:`__main__.py` marks the main entry point for the application when running it via :mod:`runpy` +(i.e. ``python -m greetings``, which works immediately with flat layout, but requires installation of the package with src layout), +so initizalize the command-line interface here: + +.. code-block:: python + + if __name__ == "__main__": + from greetings.cli import app + app() + +.. note:: + + In order to enable calling the command-line interface directly from the :term:`source tree `, + i.e. as ``python src/greetings``, a certain hack could be placed in this file; read more at + :ref:`running-cli-from-source-src-layout`. + + +``pyproject.toml`` +------------------ + +The project's :term:`metadata ` is placed in :term:`pyproject.toml`. The :term:`pyproject metadata keys ` and the ``[build-system]`` table may be filled in as described in :ref:`writing-pyproject-toml`, adding a dependency +on ``typer`` (this tutorial uses version *0.12.3*). + +For the project to be recognised as a command-line tool, additionally a ``console_scripts`` :ref:`entry point ` (see :ref:`console_scripts`) needs to be added as a :term:`subkey `: + +.. code-block:: toml + + [project.scripts] + greet = "greetings.cli:app" + +Now, the project's source tree is ready to be transformed into a :term:`distribution package `, +which makes it installable. + + +Installing the package with ``pipx`` +==================================== + +After installing ``pipx`` as described in :ref:`installing-stand-alone-command-line-tools`, install your project: + +.. code-block:: console + + $ cd path/to/greetings/ + $ pipx install . + +This will expose the executable script we defined as an entry point and make the command ``greet`` available. +Let's test it: + +.. code-block:: console + + $ greet --knight Lancelot + Greetings, dear Sir Lancelot! + $ greet --gender feminine Parks + Greetings, dear Ms. Parks! + $ greet --gender masculine + Greetings, dear Mr. what's-his-name! + +Since this example uses ``typer``, you could now also get an overview of the program's usage by calling it with +the ``--help`` option, or configure completions via the ``--install-completion`` option. + +To just run the program without installing it permanently, use ``pipx run``, which will create a temporary +(but cached) virtual environment for it: + +.. code-block:: console + + $ pipx run --spec . greet --knight + +This syntax is a bit unpractical, however; as the name of the entry point we defined above does not match the package name, +we need to state explicitly which executable script to run (even though there is only on in existence). + +There is, however, a more practical solution to this problem, in the form of an entry point specific to ``pipx run``. +The same can be defined as follows in :file:`pyproject.toml`: + +.. code-block:: toml + + [project.entry-points."pipx.run"] + greetings = "greetings.cli:app" + + +Thanks to this entry point (which *must* match the package name), ``pipx`` will pick up the executable script as the +default one and run it, which makes this command possible: + +.. code-block:: console + + $ pipx run . --knight + +Conclusion +========== + +You know by now how to package a command-line application written in Python. A further step could be to distribute you package, +meaning uploading it to a :term:`package index `, most commonly :term:`PyPI `. To do that, follow the instructions at :ref:`Packaging your project`. And once you're done, don't forget to :ref:`do some research ` on how your package is received! + +.. _click: https://click.palletsprojects.com/ +.. _docopt: https://docopt.readthedocs.io/en/latest/ +.. _typer: https://typer.tiangolo.com/ diff --git a/source/guides/installing-stand-alone-command-line-tools.rst b/source/guides/installing-stand-alone-command-line-tools.rst index 8578a3b28..c078fd1e4 100644 --- a/source/guides/installing-stand-alone-command-line-tools.rst +++ b/source/guides/installing-stand-alone-command-line-tools.rst @@ -1,3 +1,5 @@ +.. _installing-stand-alone-command-line-tools: + Installing stand alone command line tools ========================================= diff --git a/source/guides/section-build-and-publish.rst b/source/guides/section-build-and-publish.rst index 2af29d763..8e0c9ab3b 100644 --- a/source/guides/section-build-and-publish.rst +++ b/source/guides/section-build-and-publish.rst @@ -11,6 +11,7 @@ Building and Publishing dropping-older-python-versions packaging-binary-extensions packaging-namespace-packages + creating-command-line-tools creating-and-discovering-plugins using-testpypi making-a-pypi-friendly-readme