予めデータ（vv_PLF）を作成して，必要に応じてファイルに出力するコード．

vv_PLF*	get_vv_PLF	(void)
{
	static	vv_PLF	G_PLF ;
	return	&G_PLF ;
	}
static	PyObject*	check_rd	(PyObject* self, PyObject* args)
{
	vv_PLF*	gvv_plf = get_vv_PLF() ;
	vv_PLF	vv_plf_ = ::Check_Revise_deg() ;
	*gvv_plf = vv_plf_ ;
	return	Py_None ;
	}
static	PyObject*	dump_svg	(PyObject* self, PyObject* args)
{
	vv_PLF*	gvv_plf = get_vv_PLF() ;
	::Dump_SVG(*gvv_plf) ;
	return	Py_None ;
	}
static	PyObject*	dump_ipl	(PyObject* self, PyObject* args)
{
	vv_PLF*	gvv_plf = get_vv_PLF() ;
	::Dump_ipl(*gvv_plf) ;
	return	Py_None ;
	}

Python 側では
* check_rd でデータを作成．
* dump_svg などでデータを出力．

3D データを読み込んで，指定されたファイル名（拡張子により形式を判断）で出力．

static	PyObject*	load	(PyObject* self, PyObject* args)
{
	const	char*	str_file = NULL ;
	if (!PyArg_ParseTuple(args,"s",&str_file))	{
		return	NULL ;
		}
	tstring	g3_file = str_file ;
	GonsA	gnsa = ::To_GonsA(g3_file.c_str()) ;
	set_GonsA(gnsa) ;
	return	Py_None;
	}
static	PyObject*	save	(PyObject* self, PyObject* args)
{
	const	char*	str_file = NULL ;
	if (!PyArg_ParseTuple(args,"s",&str_file))	{
		return	NULL ;
		}
	tstring	g3_file = str_file ;
	GonsA*	gnsa = ::get_GonsA() ;
	::GonsA_To(*gnsa,g3_file.c_str()) ;
	return	Py_None;
	}
static	PyObject*	gons_to	(PyObject* self, PyObject* args)
{
	const	char*	str_file = NULL ;
	if (!PyArg_ParseTuple(args,"s",&str_file))	{
		return	NULL ;
		}
	tstring	g3_file = str_file ;
	gons_to(g3_file.c_str()) ;
	return	Py_None;
	}

雰囲気はつかめてきたので，以前作成した cpp を呼んでみることに…
実際の処理部分は C++ のコードだが，呼び出しは C の関数．
また引数もない状態なので，C 関数の system(“a.out”) と呼んでいるのと同様．

#include	"i_rd_dbg.hxx"
int _tmain(int argc, TCHAR* argv[])
{
	::Test_Revise_deg() ;
	return 0 ;
	}

#include	<Python.h>
#include	"i_rd_dbg.hxx"
#include	"messbar.cxx"

static	PyObject*	call_cpp(PyObject* self, PyObject* args)
{
	::Test_Revise_deg() ;
	return	Py_None ;
	}

static	PyMethodDef 	 	myMethods[] = {
	{	"_call_cpp_",	call_cpp,	METH_NOARGS,	"call cpp"		},
	{	NULL														},
	} ;

static	struct	PyModuleDef	call_mod = {
	PyModuleDef_HEAD_INIT,
	"call_mod",
	"call_cpp module",
	-1,
	myMethods
	} ;

PyMODINIT_FUNC	PyInit_call_mod(void)
{
	return	PyModule_Create(&call_mod) ;
	}

コンパイルして import まではできたが，メソッドをうまく呼び出せない．
>>> call_mod.call_cpp()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: module ‘call_mod’ has no attribute ‘call_cpp’
>>>
それで，メソッドを表示できないかと思い検索すると，
python でメソッドの一覧を取得する方法
他に dir(call_mod) もあった．

Iwao@AS5202T:/volume1/home/Iwao/test/test_py/call_c/call_cpp/T_Rvs_sc $ g++ rvs_sc_w.cpp -o call_mod.so  -fPIC -Wall -shared -I /volume1/.@plugins/AppCentral/python3/include/python3.7m/
Iwao@AS5202T:/volume1/home/Iwao/test/test_py/call_c/call_cpp/T_Rvs_sc $
Iwao@AS5202T:/volume1/home/Iwao/test/test_py/call_c/call_cpp/T_Rvs_sc $ python3
Python 3.7.0 (default, Aug 23 2018, 17:48:39)
[GCC 4.6.4] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import call_mod
>>> call_mod.call_cpp
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'call_mod' has no attribute 'call_cpp'
>>> call_mod.call_cpp()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'call_mod' has no attribute 'call_cpp'
>>> obj = call_mod
>>> import inspect
>>> for m in inspect.getmembers(obj):
...     print(m)
...
('__doc__', 'call_cpp module')
('__file__', '/volume1/home/Iwao/test/test_py/call_c/call_cpp/T_Rvs_sc/call_mod.so')
('__loader__', <_frozen_importlib_external.ExtensionFileLoader object at 0x7f5a1a35ec50>)
('__name__', 'call_mod')
('__package__', '')
('__spec__', ModuleSpec(name='call_mod', loader=<_frozen_importlib_external.ExtensionFileLoader object at 0x7f5a1a35ec50>, origin='/volume1/home/Iwao/test/test_py/call_c/call_cpp/T_Rvs_sc/call_mod.so'))
('_call_cpp_', <built-in function _call_cpp_>)
>>> call_mod._call_cpp_()
>>>