[COFF] Other OSes?

[Bakul Shah]

On Jul 8, 2018, at 5:19 PM, Dan Cross <crossd at gmail.com> wrote:
> 
> On Sun, Jul 8, 2018 at 8:12 PM Perry E. Metzger <perry at piermont.com> wrote:
> On Sun, 8 Jul 2018 16:27:54 -0700 Bakul Shah <bakul at 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.

It wasn't clear to me either. I looked at the clang webpage again
and all I see is autocompletion support for clang itself. [In a way
this points to the real problem of clang having too many options]

> 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.

When we did cisco CLI support in our router product, syntax for all
the commands was factored out. So for example

show.ip
  help IP information

show.ip.route
  help IP routing table
  exec cmd_showroutes()

show.ip.route.ADDR
  help IP address
  verify verify_ipaddr()
  exec cmd_showroutes()

etc. This was a closed universe of commands so easy to extend.

Perhaps something similar can be done, where in a command src dir
you also store allowed syntax. This can be compiled to a syntax
tree and attached to the binary using some convention. The cmd
binary need not deal with this (except perhaps when help or verify
required cmd specific support).

I ended up replicating this sort of thing twice since then.