ObserverPatternInCPP

Goals: 0. user-friendly.

1. no inheritance needed for observers and subjects.
2. provide a uniform interface with sufficient flexibility on parameter types.
3. no RTTI needed for casting parameters.

Details: C++ is known as the only "native" language that also provides great levels of abstractions. Observer pattern in C++ used to be implemented in multiple inheritances, which introduced lots of problems(name collisions and diamond relations of inheritance). Moveover, according to Wiki, some languages use RTTI to down-cast parameters, which should be avoided in C++.

Usage: see file tester.cpp