How do dolfin Parameters play with pybind11?

2

Hello,

To define an object parameters of type Parameters with the key (i.e. its name) my_parameters you can use this syntax :

  // Attempt to add parameters
  dolfin::Parameters parameters("my_parameters");

Concerning the call to to add, this function must be called inside the definition of another function in order to comply with C++ writing rules. Here is a stackoverflow post about that. For example:

[*In the cpp code snippet*]
  void add(std::string key, double pval)
  {
    my_parameters.add(key, pval);
  }
 // Function for setting a bool--valued parameter
  void add(std::string key, bool pval)
  {
    my_parameters.add(key, pval);
  }
  };

PYBIND11_MODULE(SIGNATURE, m)
{
  py::class_<Profile, std::shared_ptr<Profile>, dolfin::Expression>
    (m, "Profile")
    .def(py::init<>())
    .def("add_parameter", (void (Profile::*)(std::string, double)) &Profile::add, "Add double-valued parameter.")
    .def("add_parameter", (void (Profile::*)(std::string, bool)) &Profile::add, "Add bool-valued parameter.");
}
"""

[*In the python script*]
expr.add_parameter("p", 0.1)

However, I cannot use the modified code snippet to generate a FEniCS expression with my current installation. It generates an error similar to the one reported by Nico Schlömer a few weeks ago on this issue.