Re: Why is my thread not resuming? (very simple code inside)
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- Subject: Re: Why is my thread not resuming? (very simple code inside)
- From: Bogdan Harjoc <harjoc@...>
- Date: 2007年8月09日 18:40:58 +0200
John Klimek wrote:
Here's what I'm doing:
// ********
// startup.lua (my script)
// ********
io.write("startup: before\n");
io.write("startup: " .. AskQuestion() .. "\n");
io.write("startup: after\n");
io.write("startup: " .. nil .. "\n")
This yields an error when I try to run it: "attempt to concatenate a nil
value".
// ********
// Delphi Code
// ********
// My "C" Function
function AskQuestion(L : Lua_State) : integer; cdecl;
begin
result := lua_yield(L, 0);
end;
// Register the c-function
lua_register(L, 'AskQuestion', AskQuestion);
// Create a new thread, load a file into it, and then resume (eg. start it)
l_thread := lua_newthread(L);
lual_loadfile(l_thread, 'startup.lua'); // returns 0
lua_resume(l_thread, 0); // returns 0
I don't think this lua_resume() should return 0. According to the manual
for
v5.1, 0 is returned when your coroutine finishes.
At this point the script begins executing and prints "startup:
before". The script hits the coroutine.yield() and execution is back
inside my Delphi program.
If I try to resume the coroutine: lua_resume(l_thread, 0); it
returns "1" and does not do anything. The script does not continue.
Your AskQuestion() routine should probably return -- from the yield() --
with a
string value .. or in any case, not nil. And with lua_resume(L, 0) you are
returning nil.
That is perhaps why the second lua_resume() returns 1 -- an error code.
Since
you will be modifying your script, you might find it useful to say
something like:
ret = lua_resume(L, ...);
if (ret && ret != LUA_YIELD)
printf("error: %s\n", lua_tostring(L, -1));
What am I doing wrong?
Also, are coroutines just the name for a Lua "thread"? This is very
confusing because they seem to be two different things but I don't
know...
Hope I'm not completely missing something.
Cheers!
Bogdan