Extract and convert list element of boost::python::list

Question

I have heterogeneous list of int and string I want to store all of them in vector<string>. With this command:

    std::string temp = boost::python::extract<std::string>(xList[i][j]);

I get this error:

TypeError: No registered converter was able to produce a C++ rvalue of type std::string from this Python object of type float

Answer 1

You have two choices: either get the values as boost::python::object and check the types and do whatever you like, or register a converter that turns numbers into strings (using std::to_string presumably).

You can use the instructions for "Extracting C++ Types" in the docs:

extract<std::string&> extractor(xList[i][j]);
if (extractor.check()) {
    std::string& v = extractor();