lua_sethook and lua_yield
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- Subject: lua_sethook and lua_yield
- From: Erik Cassel <erik@...>
- Date: Tue, 5 Jun 2012 16:30:04 -0700
I've seen conflicting information on the Lua list about calling
lua_yield inside a hook. Can somebody state authoritatively if this is
supported or not?
A comment in luaV_execute code implies that it is legal (5.1 source):
if (L->status == LUA_YIELD) { /* did hook yield? */
L->savedpc = pc - 1;
return;
}
Here is a very simple test:
static void hook(lua_State* l, lua_Debug* ar)
{
lua_getinfo(l, "n", ar);
printf("Line hook %d\n", ar->currentline);
lua_yield(l, 0);
}
void debugTest()
{
lua_State* l = luaL_newstate();
luaL_openlibs(l);
lua_sethook(l, hook, LUA_MASKLINE, 0);
luaL_loadstring(l,
"for i=1,5 do\n"
" print('iteration', i)\n"
"end\n"
);
while (lua_resume(l, 0) == LUA_YIELD)
printf("Yielding\n");
}
This doesn't work. I get an infinite loop with the following output:
Yielding
Line hook 1
Yielding
Line hook 1
Yielding
Line hook 1
...
Lua never steps beyond line 1.
Thanks,
-Erik