It should be posible to install post-installation workbench dependencies

[furgo16]

Some workbenches require optional dependencies that are not critical for their functionality, but add additional features. Those optional dependencies are generally not automatically installed when the workbenches are installed (for external workbenches) or included in FreeCAD (for built-in workbenches). As such, we end up with workbenches implementint their own solutions to install those dependencies.

Here is an example for the BIM workbench, where it downloads the dependency code directly from git and places it in the macros folder (even though in this case the package is available via pip):

There should be a way to use the Addon Manager API for this (I believe not so uncommon) scenario. That would avoid duplicating FreeCAD code and arbitrarily downloading files.

[chennes]

Thinking aloud here...

A unified pip interface needs to be able to:

• Tell the Addon Manager that a given addon requires a given Python package
• Tell the Addon Manager that a given addon NO LONGER requires a given Python package
• Remove packages that are no longer required if an Addon is uninstalled
• Check if a given Python package is installed and up to date
• Update a single Python package
• Update all Python packages
• Install an arbitrary Python package without declaring a specific dependency (as a utility)
• Detect when running in a different version of Python, and synchronize its installed dependencies with all known requirements

Behind the scenes, we also need to be able to calculate the dependency graph for a given package so that we can uninstall it when no more addons require it. And that should work recursively.

Note that dependency information can be obtained via pipgrip --json <package>