Pipe is a worm hole connecting C and C++

In C programming language, the observer design pattern is implemented with function pointer (aka callback function). But in Qt library, it introduces signal and slot. How to link a callback function from the C callback function to the C++ siganl and slot is a problem I encounter. Call back function can only be static, but signal and slot can not. There are some triky way to pretend a non-static function to a static function. But the easiest way is to use pipe. the callback function create a pipe and do the read operation, while the siganl function wait for and read at the other end of the pipe.
The pipe is like a worm hole connecting C and C++, two different time and space. How cool!