Until very recently, Dropbox had a technical strategy on mobile of sharing code between iOS and Android via C++. The idea behind this strategy was simple: Write the code once in C++ instead of twice in Java and Objective C. Dropbox has now backed off from this strategy in favor of using each platforms' native languages. This decision was due to the (not so) hidden cost associated with code sharing. Join Eyal Guthmann on a journey of how Dropbox set about to share code via C++. You'll learn what went well, what went wrong, the main lessons learned, and what this means for how Dropbox writes code going forward.