OOP is a complex concept with many aspects to formalize. Moreover, programmers have used the word OOP to denote different things at different times. There are at least two kinds of OOP:
- OOP, formulated by Alan Kay, the creator of Smalltalk
- OOP with polymorphism, inheritance, and encapsulation, described by Grady Butch
The modern OOP usually refers to the latter, although the former is alive and well in many languages.
But when we discuss the second kind of OOP, we still emphasize different features in different languages. Something considered a sign of true OOP in some languages is unacceptable in others.
If we try to generalize somehow and find the most fundamental thing about all OOP languages, we will find the polymorphism of subtypes as a common ground.
Polymorphism of subtypes is probably the most important feature of modern object-oriented programming. Benjamin Pierce. Author of Types and Programming Languages
In this course, we will take an in-depth look at polymorphism. The mechanisms of its implementation, and, most importantly, learn how to apply it correctly. The main topics of this course are:
- Types of polymorphism: subtype and parametric
- Dispatching and types of dispatching
- Dependency inversion and injection
- DI container
- SOLID (SRP, OCP, LSP, ISR, DIP)
In addition, we will get acquainted with the concept of design patterns. Let us analyze their influence on code structure and get acquainted with some popular ones:
- Null Object
- Strategy
- Factory
Let us talk about when polymorphism is necessary. When it is not, or when it can even be harmful. We will look at several techniques that allow you to get polymorphic behavior without using objects. To do this, we'll look at the different types of dispatching.
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