A New One By Me

Our daughter is intensely interested in upcomming changes in her life. In particular she's aware that she is currently attending the most senior program as her pre-school (a transitional class the state will accept in lieu of kintergarten) and wants to know about where she will go to "homework school".¹

The phrase is descriptive and its meaning is clear, so it's a logical neologism, but I'd never heard it before. Is that a term of art among the pre-school set?

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¹ A very good question about which we are currently having a slow motion panic. Much research is being conducted and many experts are being consulted.

API history

So I made some progress today on the Emacs configuration improvements I mentioned in my last post.¹ That work was performed using the partially completed configuration on my Raspberry Pi 400 (i.e using Emacs 27.1).

Then I pushed and opened a machine at work to try it out in a legacy environment (using Emacs 25.2.2). No go: one of the elisp functions I used in solving a problem apparently got more robust between 25 and 27.² Check the documentation to no avail. Not surprising when I think about it: no reason the on-line³ documentation for Emacs 27 should contain any history.

But having a central source with the history is hugely useful. I regularly make heavy use of cppreference.com where APIs are exhibited annotated with the version(s) to which they apply and historical versions are listed along side their more recent counterparts. The availability of the history makes it easy to see why you can't use that StackExchange solution as is, and why the other one seems clunkier than need be.

So far, I haven't found anything equivalent for Emacs.

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¹ I also ran into that "supporting multiple versions is hard" thing even programming on a single machine. I used a function defined in the subr-x package meaning that until I re-implement that I'm limited to version 24.4 and newer. Sigh. We'll see about that re-implementation thing. I don't think I currently need to go that far back in time. If I still had to support that 2010 legacy platform it would be another issue.

² So now I'm building versions 24.4, 25.3, and 26.3 on my Pi so I can test a variety of version in one place. Might want to do a 28 and a 29, too, but let's start with what we've got, OK? Anyway, I remain impressed with the Pi, but trying to build Emacs in the background while doing other work does expose its limitations.

³ That is live-in-the-program rather than available over the network. How the language has changed, eh?

Compatability history

Have you ever noticed how hard it can be to find out which versions of software (a) were compatible with which versions of software (b)?

Documentation for software that is meant to interoperate with other software generally says something about which version(s) of the counterpart it works with, but no one has any particular reason to keep a list of the history of that relationship.

What brought this on, you ask?

I'm trying to modernize my Emacs configuration file (for which there are many luxurious options) any have reasonably uniform behavior across the several systems I work on and home and work. Alas, customer requirements at work mean I need to deal with systems dating from 2014 (and we're happy they've finally gotten serious about migrating off that platform from 2010).

All those, aforementioned, luxurious ways to configure a modern Emacs system (Spacemacs, Doom Emacs, and other "distributions") require you to be using, well, a modern version of Emacs. By which they mean v25 is definitely out and v26,fi supported at all, will soon by unsupported.

So I'm trying to do it for myself. My strategy depend on several things:

• add-package to centralize the configuration
• straight as a way to get packages
• the identification semantic categories of behavior I'd like my emacs to have and the understanding that those behaviors could be provided by different packages for different Emacs versions
• a system for selecting implementations of those categories by Emacs version number

I expect to make the project publicly available pretty soon.

But let's say my category is language server services. Popular suppliers seem to be eglot and lsp-mode. If I want to use lsp-mode on a up-to-date Emacs I'll just let straight grab the newest release of the package. But the newest version relies on variable that are not in Emacs 26, so I need an older version, but how do I learn which tag straight should get for those system?

And the problem repeats for every behavior which isn't handled internally.

Which, I suppose, is why the big distributions tell you "Use a modern Emacs, already!", albeit usually in more diplomatic terms.