I like the technique to generate compile error when there is a mismatch between format string and actual argument list and type - This is what only statically typed language can do and dynamically typed languages like python can't do.
Maybe this technique could be applied in printf or other C++ APIs using format string.
A friend of mine is recently writing C++ web framework similar to Python Flask.
It has many interesting features like compile-time routing URL parameter checking, easy and fast (probably fastest among C++ json libs) json implementation by taking full advantage of C++11.
If interested, take look of following code and repository:
Maybe this technique could be applied in printf or other C++ APIs using format string.