typing-extensions dependency

[hanson-hschang]

Describe the bug

The package fails to import due to a missing dependency. Specifically, elastica.rod.cosserat_rod attempts to import Self from typing_extensions, but typing_extensions is not automatically installed as a dependency when installing PyElastica.

To Reproduce

I installed a package that depends on PyElastica (and thus installed PyElastica). When attempting to run a basic import script, it crashes.

Script:

# run.py
import elastica as ea

Error:

Traceback (most recent call last):
  File "/Users/hschang/Desktop/RigidBodyRobotics/examples/rotation_energy_test/run.py", line 5, in <module>
    import elastica as ea
  File "/Users/hschang/Desktop/RigidBodyRobotics/.venv/lib/python3.12/site-packages/elastica/__init__.py", line 11, in <module>
    from elastica.rod.cosserat_rod import CosseratRod
  File "/Users/hschang/Desktop/RigidBodyRobotics/.venv/lib/python3.12/site-packages/elastica/rod/cosserat_rod.py", line 3, in <module>
    from typing_extensions import Self
ModuleNotFoundError: No module named 'typing_extensions'

Environment

• Python version: 3.12
• OS: macOS
• Package Manager: uv (and standard pip)
• Numpy/numba version: "numpy 2.3.5 / numba 0.63.1"
• PyElastica version: pyelastica @ git+https://github.com/GazzolaLab/PyElastica.git@update-v1

Expected behavior

import elastica should execute successfully without requiring the user to manually install internal dependencies. The typing_extensions library should be listed in the install_requires of the package configuration.

Additional context

I was able to resolve this locally by manually installing the missing module:

uv add typing-extensions
# OR
pip install typing-extensions

This suggests that typing-extensions is missing from the package's dependencies list in pyproject.toml.