Calling function with string as argument from Lua

[ChrSacher]

I am trying to call a C++ function from Lua with std::string as Argument. It fails because it expected a string but got a table. Is there a way to convert them?
Lua
Input:isKeyDown("w")

C++
bool isKeyDownS(std::string string)

[madeso]

Functions bound with State:SetObj doesn't seem to require self, so a standard dot call should suffice, however I'm facing problems with SetObj and std::string ( #141 ).
In the mean time, standard free functions seems to work fine with std::string.