The Python extension types are defined in Cython, not C or C++ so you need to load the Cython extensions in order to instantiate the classes.
Why do you have 2 copies of the C++ library? That seems easy to fix. If you are using wheels from PyPI I would recommend that you switch to conda or your own wheels without the C++ libraries bundled. On Tue, Sep 10, 2019, 4:23 PM Tim Paine <t.paine...@gmail.com> wrote: > 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 > >
