Plugin: Python3 shared libraries and Grasshopper components

Rhino Developer
, ,
1

Hi,

Is there an example open-source Grasshopper plugin that uses a shared Python3 library that I could look at?

I’ve read the “Creating Rhino/Grasshopper Script Plugins” guide (and several others), but cannot seem to load a shared Python3 library.

What I am doing:

  1. Opening ScriptEditor
  2. Importing a folder with the following structure:

asdf/
__init__.py
mylibrary.py

  1. Importing a GH definition with a Python3 Script component with code that starts with

import mylibrary (import asdf.mylibrary also doesn’t work)

The error I see is “Error getting GH_ScriptInstance instance” which disappears when I comment out the import line (and fails later with a more intelligible error when I try to use the library which wasn’t imported: “name mylibrary is not defined”).

Rhino Version:
Version 8 SR29
(8.29.26063.11001, 2026-03-04)
Commercial

Grasshopper Version: 1.0.0008

Any leads, workarounds, pointers are very welcome.

At the moment I can workaround the issue by installing the necessary packages through a custom pip package, but I’m wondering how to do this in a way that would allow me to distribute those packages together with the plugin, and not have to separately install them with pip.

Thank you!

2

Hi,

you could install your own modules as (editable) module. It essentially adds a path to the local Python currently in use. This would require some form of self-initialisation after installation. I would assume you can repeat this as often as you want.

See:

Alternatively you could provide “compiled” python modules (“pyc”) or local wheel packages. But it all ends up in adding a path to the python installation and “install” on init.

Generally speaking library management is one of the pains in Python. One of the reasons why I would not go for Python on distributed code if doable. Unless you depend on hardcore Python3 libraries its a good choice to build real shared libraries (dll, so, dylib) in the language of your choice (which might interop with CPython or C# code.

3

Thanks Tom. I have the pip approach working. The Rhino/Grasshopper Script Plugins guide makes it sound like embedding folders as packaged libraries is supported and this is what I would like to clarify. The example in that guide is for a C# folder. I am wondering if the same mechanism is intended to work with Python packages as well (and if not, I suppose the documentation could be updated to reflect that).