TEST SETUP

There is a proxy package cadquery_ocp_proxy with version 8.0.0.0 that does nothing, but have optional dependencies:

```toml
[project.optional-dependencies]
vtk = ["cadquery_ocp>=8.0,< 8.1"]
novtk = ["cadquery_ocp_novtk>=8.0,< 8.1"]
```

I built the following packages using the proxy package for testing on my local pypi server.

NOTE: These are artificial new versions to force pip and uv to load them from my pypi server, so don't get confused about the version numbers. They don't exist on pypi.org

• build123d-0.11.0-py3-none-any.whl
• cadquery-2.8-py3-none-any.whl
• ocp_gordon-0.22.0-py3-none-any.whl
• ocpsvg-0.6.0-py3-none-any.whl
• cadquery_ocp_proxy-8.0.0.0.0-py3-none-any.whl

Setup for packages in the build123d, CadQuery, or OCP ecosystem:

1. Packages with cadquery_ocp dependencies the can (like ocpsvg ocp_gordon, and build123d) would need to use extra dependencies

   dependencies = ["svgelements >= 1.9.6, <2"]
   
   [project.optional-dependencies]
   dev = ["pytest"]
   vtk = ["cadquery-ocp-proxy[vtk] >=8.0, < 8.1"]
   novtk = ["cadquery-ocp-proxy[novtk] >=8.0, < 8.1"]
   

2. Packages that need VTK like cadquery would only depend on cadquery-ocp-proxy[vtk] as default dependency

WORKFLOWS

Install build123d without VTK:

When we pip install build123d[novtk]==0.11.1, we get (pip list):

build123d               0.11.1
cadquery-ocp-novtk      8.0.0.0.0
cadquery-ocp-proxy      8.0.0.0.0
...
ocp-gordon              0.22.0
ocpsvg                  0.6.0

Tests:

• build123d: pytest --ignore=tests/test_direct_api/test_vtk_poly_data.py --ignore tests/test_direct_api/test_jupyter.py tests passes all test.
• ocpsvg: pytest tests passes all tests
• ocp_gordon: pytest tests passes all tests

Install build123d with VTK:

When we pip install build123d[vtk]==0.11.1, we get (pip list):

build123d               0.11.1
cadquery-ocp            8.0.0.0.0
cadquery-ocp-proxy      8.0.0.0.0
...
ocp-gordon              0.22.0
ocpsvg                  0.6.0

Tests:

• build123d: pytest tests passes all test.
• ocpsvg: pytest tests passes all tests
• ocp_gordon: pytest tests passes all tests

Install cadquery:

When we pip install cadquery==2.8, we get (pip list):

cadquery           2.8
cadquery-ocp       8.0.0.0.0
cadquery-ocp-proxy 8.0.0.0.0

Tests:

• cadquery: pytest tests passes all test.

Since the dependency of ocpsvg is cadquery-ocp-proxy , we can pip install ocpsvg==0.6.0

cadquery           2.8
cadquery-ocp       8.0.0.0.0
cadquery-ocp-proxy 8.0.0.0.0
...
ocpsvg             0.6.0

All good, because cadquery-ocp was already there from the cadquery installation

Tests:

• ocpsvg: pytest tests passes all test.

Tests:

• cadquery: pytest tests passes all test.
• build123d: pytest tests passes all test.
• ocpsvg: pytest tests passes all tests
• ocp_gordon: pytest tests passes all tests

Caveats

Forgetting [vtk] or novtk

What happens when we only install pip install build123d==0.11.0?

We get (pip list):

```text
build123d               0.11.1
...
ocp-gordon              0.22.0
ocpsvg                  0.6.0
```

No cadquery_ocp is installed, because it is an optional dependency . This is, unfortunately, a case where the pypi ecosystem at install time can't help any more. This needs to be covered at runtime, e.g. in __init__.py

try:
    import OCP
except ImportError:
    print("If you only want to use build123d, install 'build123d[novtk]'")
    print("When cadquery should also be installed, install 'build123d[vtk]'")

Notes:

• The same would hold for** ocpsvg.
• ocp_svg would not suffer from it, since it has build123d` as a dependency

Summary

The proxy package solves two major issue:

1. Install build123d and CadQuery in the same environment
2. Have a clear guidance on packages that should run with either cadquery_ocp and cadquery_ocp_novtk (optional dependencies)

The downside is that users need to specifiy [vtk] or [novtk] during install. This can be clearly mentioned in the Readme, but also caught at runtime to pürovide guidance for the user.