So far, we've mainly worked with classes that do not play well with other custom classes. In other words, we've defined classes that create objects that do not interact with other objects that we've created. Instead, they have methods that allow them to operate on themselves, or operate with some of the built-in Ruby classes.
In object-oriented programming, however, we write programs that reflect real-world situations and environments. In the real world, different entities are related to one another and interact with one another in various ways.
In this section we'll discuss:
- Object relationships
- Different relationships such as "belongs-to"/"has-many"
- How to use other classes and methods within another class to collaboratively send messages to one another
- Exposing data stored in a class variable
- The concept of a "join" class
In the next few lessons, we'll discuss how individual objects in object-oriented Ruby can interact with one another in ways that reflect that real-world relatedness. It's pretty hard to imagine an application without some degree of interaction, or association, between classes or models.