Nested lists std::vector<std::vector<int>>

[petrasvestartas]

Hi,

Question

I am searching for "simple" equivalent to a

• nested list in Python [[list0],[list1]...[listN]],
• when a CPP nested vector is used std::vector<std::vector<int>>.

Does it mean that it is impossible to modify python list via CPP without create a custom container?

What is working is shown below.
And the problem is described in the last section.

CPP

On CPP side I have a vector and a nested vector:

    // CPP collections visible in Python
    py::bind_vector<std::vector<int>>(m, "WoodVectorInt");
    py::bind_vector<std::vector<std::vector<int>>>(m, "WoodNestedVectorInt");

Python - simple list:

Single list [0, 2, 4] needs to converted to WoodVectorInt :

import wood_pybind11
from wood_pybind11 import test_opaque_types_wood_vector_int
from wood_pybind11 import WoodVectorInt

# this is std::vector<int>
list_of_integers = WoodVectorInt([0, 2, 4])
test_opaque_types_wood_vector_int(list_of_integers)
print(list_of_integers)

Python - nested lists are not equivalent to CPP version - PROBLEM:

Nested lists are much more not straight-forward to write.
First I must create separate collections called WoodVectorInt and then add them to the the list: WoodNestedVectorInt([list_of_integers_0, list_of_integers_1, list_of_integers_2])
QUESTION Is it possible to have a nested python list e.g. [[0,1,2],[3,4,5],[6,7,8]] and directly cast it WoodNestedVectorInt ?

import wood_pybind11
from wood_pybind11 import test_opaque_types_wood_nested_vector_int
from wood_pybind11 import WoodNestedVectorInt


# this is std::vector<std::vector<int>>
list_of_integers_0 = WoodVectorInt([0, 1, 2])
list_of_integers_1 = WoodVectorInt([3, 4, 5])
list_of_integers_2 = WoodVectorInt([6, 7, 8])
nested_list_of_integers = WoodNestedVectorInt([list_of_integers_0, list_of_integers_1, list_of_integers_2])
test_opaque_types_wood_nested_vector_int(nested_list_of_integers)
print(nested_list_of_integers[0], nested_list_of_integers[1], nested_list_of_integers[2])