Simple ECS implementation with C++
Manager class is the class that manages entire ECS.
There is only one manager class (singleton) and it can create Entity, EntityPool, Component and System.
Entity is just a pack of numbers.
Entity itself is represented with id, an unsigned integer number.
Entity does not hold any Component, but it knows where Components exist by storing Component id.
EntityPool is a pool where entities are stored.
Component is an object that holds data.
System is an object that has logic.
There are some unittests in main.cpp to see how it works. Also header is fully commneted.