Pass std::vector without copy

[petrasvestartas]

Hi,

In your examples of std::vector, data is copied.

Is there any example that shows how to bind vectors by reference instead of copy?

[tdegeus]

This example passes a list by reference : https://github.com/tdegeus/pybind11_examples/blob/master/01_py-list_cpp-vector/example.cpp

[petrasvestartas]

Dear @tdegeus ,

By returning the output, doesn't it copy the data to a new vector?

[tdegeus]

Ah @petrasvestartas . Ah yeah you are right, I did not look further than the input as I assumed your question to be about that. What is your question then actually about:

• Do you want to modify inplace? In that case you can just remove the const from the input and remove the output. This could be a nice example to add indeed. It would be great if you could open a PR.
• Do you want to return a reference to data that is owned by an object that is kept alive? In that case you can use std::vector<double>& as return object. Same here, it could be nice to add on example.

Or is your question about yet something else?

[petrasvestartas]

The second.
I think the only way to do this is by using opaque option from pybind11.