On Sun, Jul 8, 2018 at 8:12 PM Perry E. Metzger <perry@piermont.com> wrote:

On Sun, 8 Jul 2018 16:27:54 -0700 Bakul Shah <bakul@bitblocks.com>
wrote:
[snip]
> This sort of magic incantation is needed because no one has bothered
> to create a simple library for autocompletion & no standard
> convention has sprung up that a program can use.

Yes, I know. That's exactly what I'm explaining. Read the URL above.
It describes a quite general mechanism for a program to convey to the
shell, without needing any special binary support, how autocompletion
should work.

I read that article and it wasn't clear to me that the `--autocomplete` argument sent anything back to the shell. I suppose you could use it with bash/zsh style completion script to get something analogous to context-sensitive help, but it relies on exec'ing the command (clang or whatever) and getting output from it that someone or something can parse and present back to the user in the form of a partial command line; the examples they had seemed to be when invoking from within emacs and an X-based program to build up a command.

This is rather unlike how TOPS-20 did it, wherein an image was run-up in the user's process (effectively, the program was exec'ed, though under TOPS-20 exec didn't overwrite the image of the currently running program like the shell) and asked about completions. The critical difference is that under TOPS-20 context-sensitive help and completions were provided by the already-runnable/running program. In Unix, the program must be re-exec'd. It's not a terrible model, but it's very different in implementation.

- Dan C.