Week 8 (cont.)
Reference: Chapter 15
Polymorphism and Virtual Functions
Modern object-oriented (OO) languages provide 3 capabilities:
- encapsulation
- inheritance
- polymorphism
which can improve the design, structure and reusability of code.
Here, we'll explore in more detail how polymorphism can be used in C++.
What is polymorphism?
In programming languages, polymorphism means that some code or operations or objects behave differently in different contexts.
For example, the + (plus) operator in C++:
| 4 + 5 | integer addition |
| 3.14 + 2.0 | floating point addition |
| s1 + "bar" | string concatenation |
This type of polymorphism is accomplished through operator overloading, but polymorphism is not limited to operators.
C++ actually has four kinds of polymorphism:
- Subtype polymorphism, also known as runtime polymorphism.
- Parametric polymorphism, also known as compile-time polymorphism.
- Ad-hoc polymorphism, also known as overloading.
- Coercion, also known as (implicit or explicit) casting.
More about these types: http://www.catonmat.net/blog/cpp-polymorphism/
The rest of this lecture will go through several examples as part of the code in week8 of the lecture code repository -- additional notes will be posted after lecture.