An object in object-oriented language is essentially a record that contains procedures specialized to handle that record; and object types are an elaboration of record types. Indeed, in most object-oriented languages, records are just special cases of objects, and are known as plain old data structures (PODSs), to contrast with objects that use OO features.

Derived classes need to follow their base class contracts, but may choose to expose a subtype of base class with more capabilities. This includes making protected members public:

When a developer chooses to extend a class and override a method, they are consciously saying "I know what I'm doing." and for the sake of productivity that should be enough. period.

You have stumbled upon the most common problem in JSON Schema, that is, its fundamental inability to do inheritance as users expect; but at the same time it is one of its core features.

Also be aware of how Ruby handles aliases and inheritance: an alias references the method that was resolved at the time the alias was defined; it is not dispatched dynamically.

Most notably missing from the discussion is inheritance.

Multiple inheritance is one of the object oriented feature where a class or a sub class can inherit features from more than one parent class or super class.

Apparently when you create a subclass, that subclass's singleton class has # its superclass's singleton class as an ancestor.

For instance, those who prefer classical inheritance may enjoy the addition of the class keyword, while others may reject it as conflicting with the idea of a prototypical inheritance model.

Internally, it creates and returns a fresh, subclassed activity (via patching) whilst replacing the step for given :id. Be advised that this does not change the original activity class.

In order to customize the latter one and add another step tidy_storage, you’d normally have to subclass all three activities and override steps.

They claim that inheritance often breaks encapsulation, given that inheritance exposes a subclass to the details of its parent's implementation.

Informative data about objects that are considered prototypes for the role. Base concept is similar to type, but without inheritance of limitations and properties. Base concepts are designed as a substitute for inheritance for external concepts. A base concept is like a related concept except that the base concept is almost identical to the role definition.

Interface specifications can be reused through inheritance but implementation need not be.