passing std::string ref from lua to c++ function

[badetwiler]

I'm calling a c++ class member function from lua that has a std::string& argument. Once called an empty string is passed in. The correct string is passed in if I change the function's argument to accept std::string rather than std::string&. Is there any way around this by registering std::string somehow?

[jeremyong]

Can you try changing the function signature to const std::string& and see if it still happens?

[badetwiler]

changing the function signature from std::string& to std::string fixes the issue. It happens to be a 3rd partly library I'm trying to wrap, so I was trying to avoid modifying it. But it's not a huge deal. Thanks for your quick response.

[jeremyong]

Well I think this might be a bug since I am handling functions with parameter type "const std::string &" in a special way. Again, does the adding the const qualifier fix it or does the function mutate the string?

[badetwiler]

sorry I didn't state this previously; the function argument is specifically "const std::string&". When called from lua I'm seeing just an empty string passed in. Changing the argument to pass by value rather than reference fixes the issue.

[jeremyong]

Looks like I have tests for returning strings from class member functions but not sending them :P. Let's leave this open in case I have time to address it and add a new test case. Thanks!

[badetwiler]

great, thanks for the help, maybe I'll try sometime as well just to give myself a sanity check