1)write your header

2)write your webidl interface

3)use lua-webidl to generate cpp code

lua-webidl --libmode --cpp funcs.idl funcs.cpp

4)append your .hpp code to the top of your generated .cpp file

5)use a site like https://mbebenita.github.io/WasmExplorer/ or https://wasdk.github.io/WasmFiddle/ or locally compile your .cpp to WAT

6)use the WASM (WAT) file and bindings to generate the lua file with wasm2lua

wasm2lua --pureLua -b funcs.idl --libmode test.wasm funcs.lua --discardExportSymbols

• test your header file before usage
• check out https://github.com/SwadicalRag/wasm2lua/blob/master/HOWTO-BINDINGS.md
• check out https://heycam.github.io/webidl/#introduction
• make sure to initilize your member variables
• if you dont need any bindings for classes simply do step 1, 5, then wasm2lua --pureLua test.wasm funcs.lua --discardExportSymbols, heavily consider wrapping C functions in extern "C" { } for simplicity
• if you're using bindings, INLINE all functions that are going to be bound before pasting into the generated funcs.cpp
• pure lua defined env functions should be defined in env_funcs.lua where as functions requiring wasm2lua functions should be defined in intrinsics.lua
• check out the current example

• .env calls are nil

  paste the contents of intrinsics.lua to your funcs.lua inside function module.init(), if the problem persists define the needed function in env_funcs.lua

• labels bug out

  your lua version is too old

• return by value is buggy

  only use [Value] Tag for non-user defined types

• function BINDER.instantiateClass(classBase,ptr,luaOwned) issues

  replace with

  function __BINDER__.instantiateClass(classBase,ptr,luaOwned)
    local ins = setmetatable({__ptr = ptr,__luaOwned = luaOwned},classBase)
    ins.__gcproxy = {}
    if ins:__gc() ~= nil then
      getmetatable(ins.__gcproxy).__gc = function() ins:__gc() end
    end
    classBase.__cache[ptr] = ins
    return ins
  end

• __MALLOC__, replace __MALLOC__ and __FREE__ with

  local heap_start = 0
  local __MALLOC__ = function(size) 
    local temp = heap_start 
    heap_start = heap_start + size
    return temp
  end
  local __FREE__ = function() end