Solution to functions that tries modifying immutable arguments passed by reference

Hello,

Have you found any solution for handling functions that return values via output parameters passed by reference, especially when those parameters are of immutable types?

This becomes a problem with important functions like [BRep_Tool::CurveOnSurface](https://dev.opencascade.org/doc/occt-7.2.0/refman/html/class_b_rep___tool.html#aeaa70c29f0a30d827fd8a36116d74b91). In such cases, the function modifies the arguments passed by reference (e.g., to return the first and last parameters of the Geom2d_Curve), but when these are immutable types in the binding language, we can’t retrieve the modified values.

This effectively blocks access to important return data.

Some relevant references:

[pybind11 FAQ – Limitations involving reference arguments](https://pybind11.readthedocs.io/en/stable/faq.html#limitations-involving-reference-arguments)

[pyOCCT developer notes – Reference arguments](https://pyocct.readthedocs.io/en/latest/dev.html#reference-arguments)

Would appreciate any guidance or workarounds!

Thanks in advance.

Start with BRep_Tool::CurveOnSurface and review the linked pybind11 FAQ and pyOCCT developer notes on reference arguments. Determine the binding-level scope needed to expose the modified first and last curve parameters, then verify that callers can retrieve those values.

Written by the indexing model from the issue text.