trying to make a library "multiple definition of '#var'

I have just one more question regarding libraries :
Is it possible to just give compile it and send it to my friends in order to avoid them looking in the source (cpp) ?

Like a folder in Libraries with a File.h and File.o instead of File.cpp?

Not easily, and not recommended (we're all about open source). All of my arduino stuff is here: https://github.com/WizenedEE/arduino