It's one of his solutions for refactoring long methods that operate on more than one variable, so that simple "extract method" refactoring isn't feasible.

He says to turn the function into a class and local variables into private fields. So that you can split the function into small methods that operate on these private fields. I used it a few times in a company that had strict "no Sonar warnings" policy. But I hate the resulting code much more than the initial code.

The jack-in-the-box (or hellraiser's box) style of OOP. You call a succession of 0 or 1 argument methods that change the object state until suddenly something happens.