Virus engines are very similar to C/C++ classes (objects), and has many identical properties. These both substances are directed to modularity. The only difference is that C++ class has larger interface part while virus engine is oriented to implementation.
Today virus engines are on the same step as programs was many years ago, when OOP was only introduced. And now is time to change.
This text was written with a single goal: to denote characterictics of virus engine, which will make it handy and useful.