Resolve missing symbol

• Moved body of join() to header, so that it gets included in plank_drop's translation unit at compilation time

Hi David,

I couldn't comment on your question on Gazebo Answers, but I'm fairly sure this is your problem. The way C++ translation units work means that after compilation, libPlankDrop.so knows about the declaration of join(), but not the implementation. That's because the body of the function is not present in the header (extra_functions.h), which is the file that plank_drop.cc "knows about" - it's unaware of the corresponding .cc file.

Try compiling and running the - let me know if it works!

Ref: http://answers.gazebosim.org/question/21417/undefined-symbol-with-plugin/