# Object Oriented Code in the Gnus Newsreader Eric Abrahamsen [[!template id=vid src="https://mirror.csclub.uwaterloo.ca/emacsconf/2020/emacsconf-2020--32-object-oriented-code-in-the-gnus-newsreader--eric-abrahamsen.webm"]] [Download compressed .webm video (43.9M)](https://media.emacsconf.org/2020/emacsconf-2020--32-object-oriented-code-in-the-gnus-newsreader--eric-abrahamsen--compressed32.webm) [Download compressed .webm video (21.3M, highly compressed)](https://mirror.csclub.uwaterloo.ca/emacsconf/2020/smaller/emacsconf-2020--32-object-oriented-code-in-the-gnus-newsreader--eric-abrahamsen--vp9-q56-video-original-audio.webm) The venerable Gnus newsreader has evolved over the years to interface with many different types of news- or mail-like backend programs, presenting all of them using a unified interface. This sort of software often calls for an object-oriented architecture, at least as regards polymorphism, yet Gnus was written well before Emacs lisp acquired the object-oriented tools and libraries – largely borrowed from Common Lisp – that it boasts today. Yet Gnus needed something "object-oriented-like", and so nnoo.el was born: a rather amazing (and frankly terrifying) implementation of object-oriented behavior using functional code. This talk will be a brief introduction to how this existing system works, and to the ongoing, incremental effort to port it over to newer Elisp tools like generic functions, structs, and objects. <!-- from the pad ---> # Questions ## Q3: Have you done any other projects using EIEIO and/or defstruct? Right, EBDB is super deep into EIEIO, and was kind of written as a project for learning it, and the new gnus-search library is a more restrained usage. The search engines are defclasses, and much of the code is shared, which works quite well. ## Q2: Is there may activity on maintenance of Gnus today? (and is Lars involved/aware of this work?) Yes, there's still development going on. I don't think Lars is very focused on Gnus right now, but I run all changes by him first. He fixes bugs, but as far as I know, I'm the only one adding features right now, which is a terrifying thought. ## Q1: How much of this 90's funny code :) can be replaced and how much will have to stay forever? Eventually I think we can get most of it out of there. I was happy to be able to replace obarrays-as-hashtables with real hashtables, though that was a very painful process # Notes Famous last words: "Sometimes the only thing that's worse than not knowing why something doesn't work is not knowing why it does work."