pybind11 equivalent of boost::python::extract?

Question

I am considering port of a complex code from boost::python to pybind11, but I am puzzled by the absence of something like boost::python::extract<...>().check(). I read pybind11::cast<T> can be used to extract c++ object from a py::object, but the only way to check if the cast is possible is by calling it and catching the exception when the cast fails. Is there something I am overlooking?

Summerwood

Answer 1

isinstance will do the job (doc) :

namespace py = pybind11;
py::object  obj =  ...
if (py::isinstance<py::array_t<double>>(obj))
{
    ....
} 
else if (py::isinstance<py::str>(obj))
{
   std::string val = obj.cast<std::string>();
   std::cout << val  << std::endl;
} 
else if (py::isinstance<py::list>(obj))  
{
   ...
}  

Ranger

Follow-up question: how do I use this to test if the object is a Python representation of one of my classes (that was exposed to Python via pybind11)? – Naturalize

@LarryGritz idem : py::isinstance<MyCustomClass>(obj) . – Ranger