remove gdspy dependency from gdsfactory

gdsfactory is built on top of gdspy

The main issues are:

• extra dependencies makes the package harder to install and sometimes hard to follow and document
• gdspy is no longer developed (only in maintenance mode). gdstk is supposed to be the successor of gdspy
• gdspy requires conda install for windows. Now you can install gdsfactory through mamba/conda but it would be nice to only depend on one package manager such as pip

We have some options

1. switch to klayout API

• Klayout has faster booleans
• Klayout builds wheels for windows pip install klayout. So no more need to conda install gdsfactory for windows users.
• Klayout is already an optional dependency
• Klayout API is not super well documented

See @amccaugh work on the phidl klayout backed @sebastian-goeldi @thomaslima

See zeropdk

2. switch to gdstk

• gdstk is an improved version of gdspy

3. switch to rust

https://github.com/dan-fritchman/Layout21/

What do you think?

@thomasdorch @tvt173 @flaport @basnijholt

[thomaslima]

I obviously support the klayout option but disclaimer is I don’t use gdsfactory yet as I focus on zeropdk. That said, next 0.27 version will support static type checking with mypy and docstring inspection from vscode, which should be helpful for you guys. See https://github.com/KLayout/klayout/pull/1125

[joamatab]

We were able to get rid of segmentation faults in gdstk by avoiding inheritance from gdstk.Polygon and gdstk.Label

gdsfactory 6.0.0 will be released soon using gdstk backend 🎉

we also have an MVP of a klayout_backend on a branch that we will further investigate