Re: FFI and Objective C

[Eric Wing <ewmailing@...>]

On 11/18/16, Chris Jones <cmsj@tenshu.net> wrote:
> Hey
>
>> On 18 Nov 2016, at 10:24, Simon Cozens <simon@simon-cozens.org> wrote:
>> Yep, my NSLua (https://github.com/simoncozens/NSLua - heavily based on
>> EasyLua) gives you a bidirectional bridge between Lua and ObjC.
>>
>> What exactly are you looking for? Are you embedding Lua in an ObjC app,
>> or something else?
>
> Thanks for the swift reply!
>
> I currently maintain Hammerspoon (http://www.hammerspoon.org/) which uses
> Lua to expose a whole raft of OS X APIs to users (window management being
> probably the most used part).
>
> Right now I'm investigating how reasonable it would be to allow users to
> interact directly with ObjC objects from Lua (effectively allowing new OS
> API plugins to be written in pure Lua). What potentially makes this harder
> is that we already have a homegrown NSObject wrapper around Lua
> (https://github.com/Hammerspoon/hammerspoon/tree/master/LuaSkin), which
> provides some interfacing between the two, but not anything like FFI (mainly
> around converting data back and forth). I had looked at some of the
> Lua<->Cocoa bridges before, but since they generally also want to manage the
> lua_State object, it's not a simple drop-in thing :)
>
> Cheers,
> Chris
>

You might also check out LuaCocoa. It uses libffi under the hood for
some things. Maybe it could give you some ideas.

Or maybe you might be able to use it. While not perfect (some things I
would like to clean up), LuaCocoa does very hard to adhere to the Lua
philosophy of "mechanisms, not policy" and not impose on you to
conform to it (be a library and not a framework). LuaCocoa does allow
you to use a lua_State that you created yourself.

LuaCocoa uses BridgeSupport (which is part of Mac OS X) to fully and
automatically and correctly bridge all APIs on the system.

http://playcontrol.net/opensource/LuaCocoa/

I gave a talk on its design last month at the Lua Workshop. The videos
are supposed to go up soon.

-Eric