Comment 1 for bug 1764424

Hi Jérôme,
It seems related to manipulating this python tuple as a c++ object.
First, I did not see any "[]" operator for tuples in boost documentation.
Second, even if it works I'm unsure it will automatically return the correct type (a Vector3r), hence this syntax may not do what you think:
double V = tuple[i][j]
Third, you incuded a boost::python::extract(something) but the "something" is already an ordinary c++ double hence the extract is useless.
boost::python::extract is probably what you need but it should come earlier when extracting the Vector3r.
Just my guess. I hope it helps.
Bruno

https://www.boost.org/doc/libs/1_66_0/libs/tuple/doc/html/tuple_users_guide.html
https://www.boost.org/doc/libs/1_48_0/libs/python/doc/v2/ObjectWrapper.html#TypeWrapper-concept