When does it pay off to use S4 methods in R programming

Question

I program regularly in R in a professional context, and I write packages for clients or co-workers as well. Some of the programmers here have a Java background and insist on

Answer 1

Once upon a time, Roxygen2 didn't like S4 methods. As of 2017 (at least), they work together.

I've had the misfortune of creating some functions that needed methods to work with both S3 and S4 classes. It has been incredibly painful to keep this code working over the years as R-core has multiple times changed details on how these systems interact and how Namespaces work and how Rcmd check works.

If you don't like Google's style guide, then consider the comments of these well-known R package developers from this thread on R-help

Frank Harrell "If you love computer science more than you value your own time, use S4."

Terry Therneau wrote: For 90 percent of what I do I strongly prefer the loose (S3) rather than the rigid (S4) classes....My summary of S4 vs S3

S4 has a large increment in: 1. nuisance to write 2. difficulty to debug 3. ability to write very obscure code 4. design

S4 Gains: 5. ability to direct automatic conversions 6. validate the contents of a class object