inheriting from std::ofstream (to avoid rewriting same old content)...?

I would like to have some C++11 output file stream which writes to a file only if the newly written content is different from the former one (if the content is the same as the one existing on disk, I don't want to alter the original file's metadata).

FWIW, the program is on GNU/Linux/Debian/Sid x86-64, compiled by a recent GCC 5 (or later).

The reason I want to avoid overwriting an existing identical file content is because the actual output is some *.h C++ header file .... (if that matters, it is a new incarnation of a future MELT monitor, I am rewriting this in C++11) and I don't want future make builds to recompile stuff depending on it if that generated header file has not changed.

I'm tempted to inherit from std::ofstream (then, the initial file path would be some temporary path name) or std::ostringstream (then, the entire file content is kept in memory, not a big deal for my case), and redefine its close method to compare the new content with the old content on disk, and rewrite the disk file only if that content changes.

But I feel it smells not good (or even wrong), in particular because std::ofstream::close is not documented as virtual. Should I use std::filebuf instead?