  There are undeniable benefits of binding Python and C++ to take advantage of
the best features of both languages. This is especially relevant to the HEP and
other scientific communities that have invested heavily in the C++ frameworks
and are rapidly moving their data analyses to Python. Version 2 of Awkward
Array, a Scikit-HEP Python library, introduces a set of header-only C++
libraries that do not depend on any application binary interface. Users can
directly include these libraries in their compilation instead of linking
against platform-specific libraries. This new development makes the integration
of Awkward Arrays into other projects easier and more portable, as the
implementation is easily separable from the rest of the Awkward Array codebase.
The code is minimal; it does not include all of the code needed to use Awkward
Arrays in Python, nor does it include references to Python or pybind11. The C++
users can use it to make arrays and then copy them to Python without any
specialized data types - only raw buffers, strings, and integers. This C++ code
also simplifies the process of just-in-time (JIT) compilation in ROOT. This
implementation approach solves some of the drawbacks, like packaging projects
where native dependencies can be challenging. In this paper, we demonstrate the
technique to integrate C++ and Python using a header-only approach. We also
describe the implementation of a new LayoutBuilder and a GrowableBuffer.
Furthermore, examples of wrapping the C++ data into Awkward Arrays and exposing
Awkward Arrays to C++ without copying them are discussed.
