Re: Lua C API can't be used from other languages without C wrappers

[albertmcchan <albertmcchan@...>]

On Feb 21, 2018, at 6:43 AM, Chris Jones <cmsj@tenshu.net> wrote:

Hey

On 18 February 2018 at 17:37, albertmcchan <albertmcchan@yahoo.com> wrote:

And this actualy happens to me recently. I had to fix B to leave the stack alone.

IMHO it's generally better to only touch the stack in A and isolate B from Lua entirely. I tend to separate concerns like this:

Function A:

 * Validate argument types

 * Fetch argument values from the stack

 * Call function B with no lua_State access

 * Collect results from B, push whatever appropriate value(s) onto the stack

 * Return

I actually like this - unless the purpose of the function is really really simple, I always prefer to have the actual work happening in a separate function. It nicely separates the Lua glue from the actual functionality, and it's easier to test.

It might be a bit hard to follow, since we've abstracted a ton of useful Lua glue work into something called LuaSkin, but I consider this to be pretty much my ideal Lua C function:

https://github.com/Hammerspoon/hammerspoon/blob/master/extensions/streamdeck/internal.m#L130

--

Cheers,

Chris

For my case, A were originally a simple lua function that call B, C, ...

But, A should really belong inside the lib, so when I do 

lib = require 'lib', A can be called as lib.A

Had not expected calling B shared the same lua stack.

Is there a way to force calling B, C, ... with a new stack ? (like in lua ?)