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LUA: about coroutine and yield

Started by Rookie_Max Dec 23, 2004 at 6:42 PM 3 replies 3.8k views

Original Post

Dec 23, 2004 at 6:42 PM

Hi, I am a newbie of Lua and got some problem abourt coroutine of Lua Following is my code: #include // Include the Lua header and make sure the linker knows it's pure C extern "C" { #include "lua\lua.h" #include "lua\luaxlib.h" } int PrintString ( lua_State * pLuaState ) { printf("I have been run\n"); return 0; } main () { lua_State *LuaMain, *LuaThread; // Initialize a Lua state LuaMain = lua_open(); //Load Script lua_dofile(LuaMain, "test.lua"); lua_register ( LuaMain, "PrintString", PrintString); LuaThread = lua_newthread(LuaMain); lua_getglobal(LuaThread, "co_func"); lua_resume(LuaThread, 0); lua_resume(LuaThread, 0); <===== seem not work Sleep(100); return 0; } Test.lua function co_func() while 1 do PrintString() coroutine.yield() end end After I run this, I expected it will show 2 line of "I have been run" in console, but I only got one. This means the secound "lua_resume" did not work Do I have something wrong in the coding? Thanks, from Rookie

Kylotan

Dec 23, 2004 at 8:29 PM

You don't appear to have used coroutine.create(). Unlike Python, the function doesn't automatically become a coroutine just because you use 'yield' inside it. On the other hand, Lua coroutines are arguably more powerful than Python ones.

This link might help: http://lua-users.org/wiki/CoroutinesTutorial

Rookie_Max

Dec 24, 2004 at 12:55 AM

I have try to modify the lua part as follow:

function co_func()
while 1 do
PrintString()
coroutine.yield()
end
end

function co_main()
PrintString()
co = coroutine.create(co_func) <~~~seem have problem while running this line
PrintString() <===seem didn't work
coroutine.resume(co);

end

but second "PrintString()" in co_main seem didn't run.

Kylotan

Dec 24, 2004 at 8:27 AM

Well, in that case, it implies the problem is with your PrintString function, or how you're calling it, as you're seeing the issue before the coroutine even starts. You say there's a 'problem' running the coroutine line, but without saying what the problem is. Can't help there.

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