CODEWITHSUNDEEP
c++
Alejandro
Alejandro

Reputation: 949

“error: capture of non-variable” within use of lambda in a class

I have a working c++ class that has a header file and a cpp file where the following lines are in one of the functions of this class in the cpp file:

the robot(robot_ip);
   services
        .advertiseService<franka_control::SetJointImpedance>(node_handle, "set_joint_impedance",
            [&robot](auto&& req, auto&& res) { return franka_control::setJointImpedance(robot, req, res); });

I have now moved the first line above, franka::Robot robot{robot_ip};, to the header file of this class instead because I want to be able to reference robot also from other functions of this class. However, now I get the error:

error: capture of non-variable ‘CLass::robot’ 
             [&robot](auto&& req) { return sometype(robot, req, res); });
               ^~~~~

Upvotes: 1

Views: 7571

Answers (1)

Nadav Har&#39;El
Nadav Har&#39;El

Reputation: 13731

You can only capture local variables into a lambda function, because otherwise these variables will not be available to this function - you can consider this function to be a stand-alone function with extra data.

But after your change robot became a global variable, it is available inside the lambda function just like it's available to any other function - you don't need to capture it to use it (and it's not just that you don't need to - you're not allowed).

Upvotes: 3

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