Recommend pyproject.toml be used for command-lines not bin.src

Author: timj

python/cli.rst

@@ -33,11 +33,24 @@ Read more in the `argparse documentation`_.
 
 .. _argparse documentation: https://docs.python.org/3/library/argparse.html
 
+.. _add_callable_cli_command_to_your_package:
+
 Add a Callable CLI Command To Your Package
 ==========================================
 
-To create a callable command at the top level of your package create a folder called ``bin.src``.
-It should contain two files:
+If your callable command is implemented as described in :doc:`stack/argparse-script-topic-type` with a single function loading from the package implementing the script, you can define the script in the `standard Python package approach using <https://packaging.python.org/en/latest/guides/writing-pyproject-toml/#creating-executable-scripts>`_ ``pyproject.toml``.
+For example, this:
+
+.. code-block:: toml
+
+   [project.scripts]
+   exampleScript = "lsst.example.scripts.exampleScript:main"
+
+will result in a executable file appearing in ``bin/exampleScript`` that will import ``main`` from ``lsst.example.scripts.exampleScript`` and call it.
+This is the recommended way to define callable commands and all newly-written scripts should be defined this way.
+
+If your script is monolithic and includes the implementation directly in the callable script and you cannot reorganize the code, you must instead write the command to a ``bin.src`` directory at the top level.
+The directory should contain:
 
 1. ``SConscript`` with contents:
 
@@ -47,8 +60,7 @@ It should contain two files:
        from lsst.sconsUtils import scripts
        scripts.BasicSConscript.shebang()
 
-2. A file that has the name of the CLI command the user will call.
-   This file should contain as little implementation as possible.
-   The ideal simplest case is to import an implementation function and call it.
-   This makes the implementation testable and reusable.
+2. A file for each command that has the name of the CLI command the user will call.
+   This file should have a Python shebang (``#!``) in the first line.
 
+It is possible for a package to define some scripts in ``pyproject.toml`` and some scripts in ``bin.src`` but it is an error if a script is defined in both places.

stack/argparse-script-topic-type.rst

@@ -60,19 +60,9 @@ autoprogram_ generates all the content that is described by the :doc:`script top
 
 To use the autoprogram_ directive, your script needs to be set up in a particular fashion:
 
-- The script needs to be in the ``bin.src`` directory of a package, but the script file must defer its implementation to a module *inside* the package's Python modules.
+- The script needs to be defined such that the implementation is in a module *inside* the package's Python modules, with the script function specified in the package's ``pyproject.toml`` (see :doc:`python/add_callable_cli_command_to_your_package` for more information).
 
-  For example, a script file :file:`bin.src/exampleScript.py` might be structured like this:
-
-  .. code-block:: python
-
-     #! /usr/bin/env python
-
-     from lsst.example.scripts.exampleScript import main
-
-
-     if __name__ == "__main__":
-         main()
+  For example, a script file might be implemented as a ``main`` function found in ``lsst.example.scripts.exampleScript`` and be defined as a command line program called ``exampleScript``.
 
 - The `argparse.ArgumentParser` instance must be generated by an argument-less function.
   This is critical for letting the autoprogram_ directive get a copy of the `~argparse.ArgumentParser` instance to introspect the command-line interface: