The Strategy Pattern -- Rainer Grimm
A canonical example:
The Strategy Pattern
by Rainer Grimm
From the article:
Purpose: Defines a family of algorithms and encapsulates them in objects
Also known as: Policy
Use case:
- Different variations of an algorithm are needed
- The client does not need to know the algorithm
- The algorithm should be exchangeable at the run time of a program...

Const... times four:
constexpr keeps getting more and more powerful with each release:
Playing the classics, at arm's length...
When having the "last word" makes stuff go faster...
As Crocodile Dundee famously said, "That's not a loop, that's a loop." Just programmers having fun: