Very cool work:

Runtime-Complied C++ blog

This technique allows you to change your C++ code while it's running.

It uses no scripting, no VM, no external tools -- you can apply it to your own code and you can continue to use your favourite IDE. We think the quit-recompile-restart-reload cycle we're all used to could soon be a thing of the past.

If this is your first visit, watch the teaser video on the left.

If you want to know more, start here

dougbinks writes on the Reddit comment thread:

Compiling and loading code at runtime certainly isn't new, but what we're trying to do is develop a permissive open source portable and standard C++ solution which makes it easy to use. Cling is another similar project, but it uses compiler changes to LLVM so you need to use that compiler, whereas our solution requires only small changes to get it working with any compiler (currently supporting Visual Studio, gcc, clang/llvm).