I'm trying to add an expression as default arguments to my python function API, which is implemented by pybind11.
For example, here's the C++ function:
void my_print(std::chrono::system_clock::time_point tp = std::chrono::system_clock::now()) {
std::cout << tp << std::endl;
}
PYBIND11_MODULE(my_module, m) {
m.doc() = "my python module implement in pybind11";
m.def("my_print", &my_print, py::arg("tp") = std::chrono::system_clock::now());
}
Now I'm wonderring that, the expression = std::chrono::system_clock::now()
, I want it been called everytime I invoke this my_print
API in python script.
But I'm not sure, is this expression been called everytime this API been invoked in python ? Or this expression is only been called once when this python module been load in python ?
This is evaluated once, during the (runtime) initialization of the pybind bindings.
The way this feature is implemented is by overloading operator=
of py::arg
to return a different type, py::arg_v
(short for argument with default value).