I won't argue that the first example is cleaner, but both seemingly simple examples have a major issue. Lifetime. The observer pattern is notorious for being o

I won't argue that the first example is cleaner, but both seemingly simple examples have a major issue. Lifetime. The observer pattern is notorious for being overly complicated in C++ because you have to ensure Observer and Observable keep valid references to each other. "Modern C++" (what ever that is nowadays) leverages RAII (i.e. scope-based resource management) to improve upon the situation. With your typical observer (i.e. signal/slots) library you get a "scoped connection" object when registering the callback function. You store that object in your class and when it is destroyed, it breaks the connection. Furthermore, it facilitates the implementation of correct copy and move semantics. It's not that people don't "understand" C++, the problem is that there are so so many things to watch out for, even in simple use-cases, that even experienced C++ programmers make mistakes on a regular basis.