先日 Python から C を呼び出す関係を調べていて Synology NAS に Python.h がなかった．
検索 をかけると DSM「パッケージ センター」－「Python3」では python-dev が入ってないらしい．

次の様な手順で python-dev をインストール．
# sudo -i
# cd /var/services/homes/Iwao/
# source ./set_ds_inc.sh
# opkg install python-dev
# opkg install python3-dev

コンパイルで必要なファイルは次の所に入った．
/volume1/@entware-ng/opt/include/python3.6/Python.h
/volume1/@entware-ng/opt/include/python2.7/Python.h

Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ g++ g3d_to.cpp -Wall -fPIC -o g3d_to.so -shared
g3d_to.cpp:9:20: fatal error: Python.h: No such file or directory

                    ^
compilation terminated.
Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ g++ g3d_to.cpp -Wall -fPIC -o g3d_to.so -shared -I /volume1/@entware-ng/opt/include/python3.6/
Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ ll
total 9568
drwxrwxrwx+ 3 Iwao users    4096 Aug  5 10:29 .
drwxrwxrwx+ 3 Iwao users    4096 Aug  5 09:50 ..
-rwxrwxrwx+ 1 Iwao users 3941375 May  7 18:03 3887.imo
-rwxrwxrwx+ 1 Iwao users 1241865 Jul  7 15:13 7801.imo
drwxrwxrwx+ 2 Iwao users    4096 Aug  5 10:29 bak
-rwxrwxrwx+ 1 Iwao users    1688 Aug  4 15:04 g3d_to.cpp
-rwxrwxrwx  1 Iwao users 2654136 Aug  5 10:29 g3d_to.so
-rwxrwxrwx+ 1 Iwao users    1644 Aug  7  2019 gons_to.cpp
-rwxrwxrwx  1 Iwao users 1931244 Aug  5 10:17 gons_to.out
Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ python3
Python 3.6.2 (default, Jan 11 2018, 10:32:53)
[GCC 6.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import g3d_to
>>> dir(g3d_to)
['__doc__', '__file__', '__loader__', '__name__', '__package__', '__spec__', 'gons_to', 'load', 'save']
>>> g3d_to.load("./7801.imo")
>>> g3d_to.save("./7801.stl")
>>> g3d_to.save("./7801.ac")
>>>
Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ ll
total 10252
drwxrwxrwx+ 3 Iwao users    4096 Aug  5 10:31 .
drwxrwxrwx+ 3 Iwao users    4096 Aug  5 09:50 ..
-rwxrwxrwx+ 1 Iwao users 3941375 May  7 18:03 3887.imo
-rwxrwxrwx+ 1 Iwao users  438369 Aug  5 10:31 7801.ac
-rwxrwxrwx+ 1 Iwao users 1241865 Jul  7 15:13 7801.imo
-rwxrwxrwx+ 1 Iwao users  254784 Aug  5 10:31 7801.stl
drwxrwxrwx+ 2 Iwao users    4096 Aug  5 10:29 bak
-rwxrwxrwx+ 1 Iwao users    1688 Aug  4 15:04 g3d_to.cpp
-rwxrwxrwx  1 Iwao users 2654136 Aug  5 10:29 g3d_to.so
-rwxrwxrwx+ 1 Iwao users    1644 Aug  7  2019 gons_to.cpp
-rwxrwxrwx  1 Iwao users 1931244 Aug  5 10:17 gons_to.out
Iwao@DS116:~/pyt_test/call_c/call_cpp/g3d_to$ 

コンパイル，実行など AS5202T より時間がかかる．

https://jml.mish.work/python/call-c-python.html