Re: good examples of Emacs modules?

[Aurélien Aptel]

Hi all,

On Thu, Mar 31, 2016 at 10:23 PM, Óscar Fuentes <address@hidden> wrote:
> consequences.) How objects created by the module system interact with
> garbage collection is an start.

Every emacs_value allocated inside a Lisp-exposed function becomes
invalid when control of the function ends (when it exits) unless you
return that value or you mark it global with the the
env->make_global_ref() API call.

As I was googling for a browseable emacs git repo to look quickly at
emacs-module.h I've noticed that Syohei Yoshida (cc'ed) has figured a
lot of things out by himself (kudos to you!) and has already made some
simple and not-so-simple modules:

- dead simple module that exposes an ioctl syscall to Lisp
  https://github.com/syohex/emacs-eject

- json parser/encoder
  https://github.com/syohex/emacs-parson
  this one is interesting because he has done some benchmarks!

- libGeoIP binding
  https://github.com/syohex/emacs-geoip

- libbarcode binding
  https://github.com/syohex/emacs-barcode

- libmemcached binding
  https://github.com/syohex/emacs-memcached

- libyaml binding
  https://github.com/syohex/emacs-libyaml

- libqrencode binding
  https://github.com/syohex/emacs-qrencode

- embedded Lua interpreter
  https://github.com/syohex/emacs-lua

- embedded Ruby interpreter
  https://github.com/syohex/emacs-mruby-test

- wrapper that lets you implement modules in Nim
  https://github.com/yuutayamada/nim-emacs-module

I've looked briefly at most of them and I think they are good
examples. Especially how he only implements low-level functionality of
package xyz in a xyz-core module which is exactly how I envisioned it.

- Tom Tromey has also made a binding on libffi which means you can
call C stuff from Lisp without writing a module.
  https://github.com/tromey/emacs-ffi

It seems the japanese-speaking Emacs community has picked up on the
modules feature quite fast. I found several article/blog about it. Too
bad I can't read it, it looks interesting :)

- article on how the emacs-eject module was done
  http://syohex.hatenablog.com/entry/2015/12/16/185458
- article on the module feature with *benchmarks* and side-by-side
code comparison. Very cool!
  http://coldnew.github.io/blog/2015/01/03_emacsdynamic/

Syohei, I really like what you did and I would be interested in your
feedback on what could be improved, what should we add&optimize in the
module API, etc.

Thanks!