Fix unused parameter warnings

Some of the parameters are unused,  and the best way to silence the warning is to remove the parameter name, which is what this patch does. Something I wasn't sure of was the removal of the `attr` parameter, which defaulted to a default constructed `std::string` but it was used nowhere.

The main reason why warnings can be annoying or cumbersome is due to the fact that some people (such as myself) compile with `-Werror` and treat all warnings as errors.