Over on the Fediverse, I said something that has a story attached :

It sounds obvious to say it, but I need to remember that I can always switch buffers in GNU Emacs by just switching buffers, not by using, eg, the MH-E commands to switch (back) to another folder. The MH-E commands quite sensibly do additional things, but sometimes I don't want them.

GNU Emacs has a spectrum of things that range from assisting your conventional editing (such as LSP clients) to what are essentially nearly full-blown applications that happen to be embedded in GNU Emacs, such as magit and MH-E and the other major modes for reading your email (or Usenet news, or etc). One of my personal dividing lines is to what extent the mode takes over from regular Emacs keybindings and regular Emacs behaviors. On this scale, MH-E is quite high on the 'application' side; in MH-E folder buffers, you mostly do things through custom keybindings.

(Well, sort of. This is actually overselling the case because I use regular Emacs buffer movement and buffer searching commands routinely, and MH-E uses Emacs marks to select ranges of messages, which you establish through normal Emacs commands. But actual MH-E operations, like switching to another folder, are done through custom keybindings that involve MH-E functions.)

My dominant use of GNU Emacs at the moment is as a platform for MH-E. When I'm so embedded in an MH-E mindset, it's easy to wind up with a form of tunnel vision, where I think of the MH-E commands as the only way to do something like 'switch to another (MH) folder'. Sometimes I do need or want to use the MH-E commands, and sometimes they're the easiest way, but part of the power of GNU Emacs as a general purpose environment is that ultimately, MH-E's displays of folders and messages, the email message I'm writing, and so on, are all just Emacs buffers being displayed in Emacs windows. I don't have to switch between these things through MH-E commands if I don't want to; I can just switch buffers with 'C-x b'.

(Provided that the buffer already exists. If the buffer doesn't exist, I need to use the MH-E command to create it.)

Sometimes the reason to use native Emacs buffer switching is that there's no MH-E binding for the functionality, for example to switch from a mail message I'm writing back to my inbox (either to look at some other message or to read new email that just came in). Sometimes it's because, for example, the MH-E command to switch to a folder wants to rescan the MH folder, which forces me to commit or discard any pending deletions and refilings of email.

One of the things that makes this work is that MH-E uses a bunch of different buffers for things. For example, each MH folder gets its own separately named buffer, instead of MH-E simply loading the current folder (whatever it is) into a generic 'show a folder' buffer. Magit does something similar with buffer naming, where its summary buffer isn't called just 'magit' but 'magit: <directory>' (I hadn't noticed that until I started writing this entry, but of course Magit would do it that way as a good Emacs citizen).

Now that I've written this, I've realized that a bit of my MH-E customization uses a fixed buffer name for a temporary buffer, instead of a buffer name based on the current folder. I'm in good company on this, since a number of MH-E status display commands also use fixed-name buffers, but perhaps I should do better. On the other hand, using a fixed buffer name does avoid having a bunch of these buffers linger around just because I used my command.

(This is using with-output-to-temp-buffer , and a lot of use of it in GNU Emacs' standard Lisp is using fixed names, so maybe my usage here is fine. The relevant Emacs Lisp documentation doesn't have style and usage notes that would tell me either way.)