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Here is a little scenario that I want to use:

-- /tmp/test.lua --
function test()
-- end tmp/test.lua --

cfunc is a function defined in C++ like this:

-- cut here --
int w_cfunc_call(lua_State *pLuaState)
    //Get the parameters from pLuaState

   //I enqueue a request. I don't know when it will finish
   //It will run in a separate thread. When it will be finished
   //I will get signaled and I will do a lua_resume. Till then
   //we must issue a lua_yield


    return 1;

lua_pushcfunction(pLuaState, w_cfunc_call);
lua_setglobal(pLuaState, "cfunc");

-- end cut --

Basically, when I do `a=cfunc(123)` it will take a looong time (database access). I want to yield the current coroutine from C++ so the lua script writer won't feel anything. But When I run my app I get '/tmp/test.lua: attempt to yield across metamethod/C-call boundary'

To further summarize the problem:

1. Have a c++ working thread that gets it's work chunk from a queue
2. Wrap all the internals in a c++ function callable from Lua
	a. enqueue the work chunk
	b. yield Lua
	c. wait for the results from thread (we will get signaled)
	d. resume Lua by invoking lua_resume
3. The writer of the Lua script must not know anything about the internals of the call (we must not force him to make a yield/resume from Lua)

Is this possible?