provide standard pagination links in RSS/Atom feeds

[jameysharp]

Since feeds use the same query parameters as the rest of WordPress, it's already possible to get RSS/Atom-format lists of older posts in addition to the newest 10 (or whatever posts_per_rss is set to). However, a client has to know it's looking at a WordPress-generated feed, and manually construct the right paginated feed URLs.

I'd like WordPress to implement the Atom pagination links standardized in 2007 by ​RFC 5005, which also has an appendix on using them in RSS.

I've written a plugin demonstrating how to do this in a spec-conformant way (​https://github.com/jameysharp/wp-fullhistory). The spec requirements that enable aggressive caching in feed readers make the "obvious" ways to do this not work, but the plugin is still quite simple. I've included extensive comments if you're interested in the details, and the plugin passes WordPress coding standards 2.2.0. But PHP isn't one of the languages I normally use, so I'd certainly appreciate code review.

I brought this up in the forums a while back (​post) and got very helpful starting points from Samuel Wood, but my current implementation is much simpler than I had thought it would be.

I've considered just encouraging people to use the plugin, rather than trying to get this standard supported in core. But there already aren't very many WordPress users who know what RSS is, let alone understand extensions. (I surveyed several dozen webcomic creators, in particular.)

So for the same reasons that it's good for the open web that WordPress just automatically provides feeds, I hope you'll automatically provide standard pagination in those feeds too.

[SergeyBiryukov]

Related: #55909