LÖVE

Posted: **Tue Jun 04, 2013 1:21 am**

Hi,

I'm desadoc/Erivaldo from Brazil, I'm new to love2D and this is my first post here. Please forgive my english and typos

Early today I wrote some code with resume/yield that didn't work. The code was +- like this:

Code: Select all

-- main.lua
function love.load()
 local co = coroutine.create(function() dofile("myscript.lua") end)
 coroutine.resume(co)
end

-- myscript.lua
coroutine.yield()

The stack trace told me the problem was an "attempt to yield across metamethod/C-call boundary...". I googled that and found that Lua 5.2 and Coco/LuaJIT supposedly support that kind of yield. I decided to try love2D with Lua 5.2 first and the error, as I expected, disappeared. Then I tried LuaJIT. All builds that I found here in the forum gave me the same error. The last test I did was to download the latest stable LuaJIT, compile it and try the following code (that runs fine with Lua 5.2 too):

Code: Select all

local function hook(event, line)
 print(debug.traceback())
 coroutine.yield()
end

local pr = assert(load("print\"hi?\""))
local cr = coroutine.create(pr)
debug.sethook(cr, hook, "clr")

print(coroutine.resume(cr))

Is LuaJIT really broken? Or is it my fault? And in that case, is there some way to write that code so it works with LuaJIT too?

Posted: **Tue Jun 04, 2013 3:58 am**

Hi, please take a look at Lua 5.1 manual: http://www.lua.org/manual/5.1/manual.ht ... tine.yield
LuaJIT is based on Lua 5.1. I believe your problem is that coroutines in 5.1 cannot yield across a C function (dofile). If you want your code to work in 5.1, you should use loadfile to return a Lua function and pass it to coroutine.create.

Posted: **Wed Jun 05, 2013 3:26 am**

Thanks, markgo, that worked

But I noticed that although the first code works now with loadfile in Lua 5.1 or LuaJIT (or dofile only in Lua 5.2), the second code snippet I posted only works while using Lua 5.2 or LuaJIT through love2D. The stand alone interpreter of both Lua 5.2 and LuaJIT 2.0.2 crashes with that error.

Posted: **Tue Sep 10, 2013 8:46 pm**

I'm having the problem with yield: doing it from the hook kills the coroutine.

Code: Select all

function f ( )
 print ( "enter" )
 function hook ( )
  print ( "hooked" )
  coroutine.yield ( )
 end
 
 debug.sethook ( hook, "", 10 )
 while true do
  print ( "test" )
 end
end

local c = coroutine.create ( f )
coroutine.resume ( c )
print ( coroutine.status ( c ) )
coroutine.resume ( c )
print ( coroutine.status ( c ) )


output:
enter
test
test
hooked
dead
dead

It works the same way both in LÖVE and Lua demo on the official website, ~~although I couldn't find any evidence of this on the net~~(silly me) it's the same error as in OP, but suggestions didn't worked. Additionally, reducing the snippet to the bare minimum, with only printing coroutine status after it's resumed (no C calls until after yield) gives same result. Does anyone knows how do I work around this?

LÖVE

Lua 5.2 and LuaJIT resume/yield issue

Lua 5.2 and LuaJIT resume/yield issue

Re: Lua 5.2 and LuaJIT resume/yield issue

Re: Lua 5.2 and LuaJIT resume/yield issue

Re: Lua 5.2 and LuaJIT resume/yield issue