Is there no way to do it without PyArrow? My C++ library is building arrow itself, which means if I use PyArow I’ll end up having 2 copies: one from my local C++ only build, and one from PyArrow.
> On Sep 10, 2019, at 5:18 PM, Wes McKinney <wesmck...@gmail.com> wrote: > > hi Tim, > > You can use the functions in > > https://github.com/apache/arrow/blob/master/cpp/src/arrow/python/pyarrow.h > > You need to call "import_pyarrow()" from C++ before these APIs can be > used. It's similar to the NumPy C API in that regard > > - Wes > > On Tue, Sep 10, 2019 at 4:13 PM Tim Paine <t.paine...@gmail.com> wrote: >> >> Hey all, following up on a question I asked on stack overflow >> <https://stackoverflow.com/questions/57863751/how-to-convert-pyarrow-table-to-arrow-table-when-interfacing-between-pyarrow-in>. >> >> It seems there is some code >> <https://arrow.apache.org/docs/python/extending.html#_CPPv412unwrap_tableP8PyObjectPNSt10shared_ptrI5TableEE> >> in PyArrow’s C++ to convert from a PyArrow table to an Arrow table. The >> problem with this is that my C++ library >> <https://github.com/finos/perspective> is going to build and link against >> Arrow on the C++ side rather than PyArrow side (because it will also be >> consumed in WebAssembly), so I want to avoid also linking against PyArrow’s >> copy of the arrow library. I also need to look for PyArrow’s header files, >> which might conflict with the version in the local C++ code. >> >> My solution right now is to just assert that PyArrow version == Arrow >> version and do some pruning (so I link against local libarrow and PyArrow’s >> libarrow_python rather than use PyArrow’s libarrow), but ideally it would be >> great if there was a clean way to hand a PyArrow Table over to C++ without >> requiring the C++ to have PyArrow (e.g. using only a PyObject *). Please >> forgive my ignorance/google skills if its already possible! >> >> unwrap_table code: >> https://github.com/apache/arrow/blob/c39e3508f93ea41410c2ae17783054d05592dc0e/python/pyarrow/public-api.pxi#L310 >> >> <https://github.com/apache/arrow/blob/c39e3508f93ea41410c2ae17783054d05592dc0e/python/pyarrow/public-api.pxi#L310> >> >> library pruning: >> https://github.com/finos/perspective/blob/python_arrow/cmake/modules/FindPyArrow.cmake#L53 >> >> <https://github.com/finos/perspective/blob/python_arrow/cmake/modules/FindPyArrow.cmake#L53> >> >> >> >> >> Tim
