How can I bind a constructor to take python arguments, with defaults, that don't match my C++ constructor?

[dograt]

For example, say I have MyCppClass(const Eigen::MatrixXd& arg). How do I bind this so that it can accept an nb::ndarray type instead? It looks like nb::init requires an exact type match.

I can handle the conversions to the types, I'm just not sure how to actually bind this. Especially when I have default values. For example:

.def("__init__",
    // Manual constructor wrapper to convert numpy arrays to Eigen::MatrixXd
    [](MyType* self,
       nb::ndarray<> my_matrix_object) {
        // Use defaults if Python args are None
        MatrixXd m_mat = numpy_to_eigen(my_matrix_object);

        new (self) MyType(m_mat);
    },
    "my_matrix_object"_a = eigen_to_numpy(MatrixXd::Zero(1, 4))
    )

This compiles, but does not recognize that I have a default argument, or something like that. When I try to create MyType() in Python, I get a argument mismatch error.