As I understand I got a code review that my module has behavior and state at the same time, what does it mean anyway ?
Isn’t that the whole point of object oriented programming, that instead of operating on data directly with logical circuitry using functions. We choose to operate on these closed black-boxes (encapsulation) using a set of neatly designed keys, switches and gears.
Wouldn’t such a scheme naturally contain data(state) and logic(behavior) at the same time ?
By module I mean : a real Ruby module.
I designed something like this : How to design an application keeping SOLID principles and Design Patterns in mind
and implemented the commands in a module which I used to mixin.
Whatever you are referring to, be it an object defined by a class (or type), a module, or anything else with code in it, state is data that is persisted over multiple calls to the thing. If it “remembers” anything between one execution and the next, then it has state.
Behavior, otoh, is code that manipulates or processes that state-data, or non-state data that is used only during a single execution of the code, (like parameter values passed to a function). Methods, subroutines or functions, anything that changes or does something is behavior.
Most classes, types, or whatever, have both data (state) and behavior, but….
Some classes or types are designed simply to carry data around. They are referred to as Data Transfer objects or DTOs, or Plain Old Container Objects (POCOs). They only have state, and, generally, have little or no behavior.
Other times, a class or type is constructed to hold general utility functions, (like a Math Library). It will not maintain or keep any state between the many times it is called to perform one of its utilities. The only data used in it is data passed in as parameters for each call to the library function, and that data is discarded when the routine is finished. It has behavior. but no state.