The reason I wrote an extra chapter for Object-oriented Programming in R was to make it longer before I sell it. Apress have shown interest in both that book and Meta-programming in R, and both are on the short side. Both are currently shorter than the Functional Programming in R book we just finished the proofs of, and that is only around 100 pages in their formatting.
Unfortunately, while I thought they would be interested in the object-oriented book first, they are more interested in the meta-programming book, so I need to add some stuff to that soon.
I’m just not entirely sure what extra topics I should cover. I think I have covered all the essentials in the current version. If anyone has any ideas, I would love to hear them. Otherwise, I will dream up an example of an embedded domain specific language and write a chapter on that.