我试图从C++调用lua函数,并且不断收到错误消息“错误:尝试调用nil值”。“尝试调用lua脚本时尝试调用nil值”
lua函数创建一个C++对象,然后调用它的一个方法,胶水代码已经用tolua ++生成。当调用lua函数时,我传递了一个lua_State指针,因为C++类需要一个用于其构造函数的函数,而lua函数将这个函数交给它。
但据我所知,它永远不会那么远,它根本不运行脚本。至少该错误不会引用脚本中的任何行号。
这里是C++代码调用该函数:
int main()
{
lua_State *lState;
lState = luaL_newstate(); //new lua state
tolua_TestClass_open (lState); //open libs for TestClass
int iStatus = luaL_loadfile(lState, "lua1.lua"); //load script
if (iStatus)
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
iStatus = lua_pcall(lState, 0, 0, 0); //initialise the lua script
if(iStatus)
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
lua_getglobal(lState, "lua1Function"); //starting the function call
lua_pushlightuserdata (lState, lState); //lState is also being passed in as a parameter
iStatus = lua_pcall(lState, 1, 0, 0); //calling on this lua state with 1 argument expecting 0 outputs
if(iStatus) //error checking
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
return 1;
}
下面是LUA脚本:
function lua1Function(lstate)
tclass = TestClass:new();
tclass:method1();
tclass:method3();
end
我相当肯定它不是忘了做简单的事情:
tclass = TestClass:new(lstate);
由于胶水代码似乎表明我不需要那样做,因此:
/* method: new of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_new00
static int tolua_TestClass_TestClass_new00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertable(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnoobj(tolua_S,2,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
lua_State* tolua_var_1 = tolua_S; //seems to know I want the lua_State by default,
//usually it will pop a usertype or luanumber or whatever off the stack,
//depending on the parameter
{
TestClass* tolua_ret = (TestClass*) Mtolua_new((TestClass)(tolua_var_1));
tolua_pushusertype(tolua_S,(void*)tolua_ret,"TestClass");
}
}
return 1;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'new'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
而产生的错误信息似乎证实了我的理论:“函数错误new”。参数#2是'userdata'; '[no object]'expected。“ 即它不期望/不需要我通过那个lua_State指针
我很茫然,我很难找到问题的解决方案lua,因为在tolua ++的基础上,教程/文档似乎很薄弱,但现在改变绑定库已经太晚了。
任何帮助都会非常感谢,我希望我已经提供了足够的诊断问题。
编辑:这是我的TestClass.cpp代码(你可以忽略方法1,2和3,因为它们似乎没有被调用,因为这个错误r):
#include "TestClass.h"
#include <iostream>
TestClass::TestClass(lua_State *L)
{
num = NULL;
lState = L;
}
int TestClass::method1()
{
int iStatus = luaL_loadfile(lState, "lua2.lua");
if (iStatus)
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
iStatus = lua_pcall(lState, 0, 0, 0); //this might be to initialise the lua script
if(iStatus)
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
///////////call lua function, passing on self pointer onto the stack////////////////
lua_getglobal(lState, "lua2Function");
tolua_pushusertype(lState, this, "TestClass");
iStatus = lua_pcall(lState, 1, 1, 0);
if(iStatus) //error checking
{
std::cout << "Error: " << lua_tostring(lState, -1);
return 1;
}
///////////lua function returns an int, return it////////////
num = lua_tointeger(lState, -1);
return 0;
}
int TestClass::method2(int i)
{
i += 2;
return i;
}
void TestClass::method3()
{
std::cout << (char)num << std::endl;
}
/*
** Lua binding: TestClass
** Generated automatically by tolua++-1.0.92 on 04/05/11 17:59:24.
*/
#ifndef __cplusplus
#include "stdlib.h"
#endif
#include "string.h"
#include "tolua++.h"
/* function to release collected object via destructor */
#ifdef __cplusplus
static int tolua_collect_TestClass (lua_State* tolua_S)
{
TestClass* self = (TestClass*) tolua_tousertype(tolua_S,1,0);
Mtolua_delete(self);
return 0;
}
#endif
/* function to register type */
static void tolua_reg_types (lua_State* tolua_S)
{
tolua_usertype(tolua_S,"TestClass");
}
/* method: new of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_new00
static int tolua_TestClass_TestClass_new00(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertable(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnoobj(tolua_S,2,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
lua_State* tolua_var_1 = tolua_S;
{
TestClass* tolua_ret = (TestClass*) Mtolua_new((TestClass)(tolua_var_1));
tolua_pushusertype(tolua_S,(void*)tolua_ret,"TestClass");
}
}
return 1;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'new'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
/* method: new_local of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_new00_local
static int tolua_TestClass_TestClass_new00_local(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertable(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnoobj(tolua_S,2,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
lua_State* tolua_var_1 = tolua_S;
{
TestClass* tolua_ret = (TestClass*) Mtolua_new((TestClass)(tolua_var_1));
tolua_pushusertype(tolua_S,(void*)tolua_ret,"TestClass");
tolua_register_gc(tolua_S,lua_gettop(tolua_S));
}
}
return 1;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'new'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
/* method: method1 of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_method100
static int tolua_TestClass_TestClass_method100(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertype(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnoobj(tolua_S,2,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
TestClass* self = (TestClass*) tolua_tousertype(tolua_S,1,0);
#ifndef TOLUA_RELEASE
if (!self) tolua_error(tolua_S,"invalid 'self' in function 'method1'", NULL);
#endif
{
int tolua_ret = (int) self->method1();
tolua_pushnumber(tolua_S,(lua_Number)tolua_ret);
}
}
return 1;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'method1'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
/* method: method2 of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_method200
static int tolua_TestClass_TestClass_method200(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertype(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnumber(tolua_S,2,0,&tolua_err) ||
!tolua_isnoobj(tolua_S,3,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
TestClass* self = (TestClass*) tolua_tousertype(tolua_S,1,0);
int tolua_var_2 = ((int) tolua_tonumber(tolua_S,2,0));
#ifndef TOLUA_RELEASE
if (!self) tolua_error(tolua_S,"invalid 'self' in function 'method2'", NULL);
#endif
{
int tolua_ret = (int) self->method2(tolua_var_2);
tolua_pushnumber(tolua_S,(lua_Number)tolua_ret);
}
}
return 1;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'method2'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
/* method: method3 of class TestClass */
#ifndef TOLUA_DISABLE_tolua_TestClass_TestClass_method300
static int tolua_TestClass_TestClass_method300(lua_State* tolua_S)
{
#ifndef TOLUA_RELEASE
tolua_Error tolua_err;
if (
!tolua_isusertype(tolua_S,1,"TestClass",0,&tolua_err) ||
!tolua_isnoobj(tolua_S,2,&tolua_err)
)
goto tolua_lerror;
else
#endif
{
TestClass* self = (TestClass*) tolua_tousertype(tolua_S,1,0);
#ifndef TOLUA_RELEASE
if (!self) tolua_error(tolua_S,"invalid 'self' in function 'method3'", NULL);
#endif
{
self->method3();
}
}
return 0;
#ifndef TOLUA_RELEASE
tolua_lerror:
tolua_error(tolua_S,"#ferror in function 'method3'.",&tolua_err);
return 0;
#endif
}
#endif //#ifndef TOLUA_DISABLE
/* Open function */
TOLUA_API int tolua_TestClass_open (lua_State* tolua_S)
{
tolua_open(tolua_S);
tolua_reg_types(tolua_S);
tolua_module(tolua_S,NULL,0);
tolua_beginmodule(tolua_S,NULL);
#ifdef __cplusplus
tolua_cclass(tolua_S,"TestClass","TestClass","",tolua_collect_TestClass);
#else
tolua_cclass(tolua_S,"TestClass","TestClass","",NULL);
#endif
tolua_beginmodule(tolua_S,"TestClass");
tolua_function(tolua_S,"new",tolua_TestClass_TestClass_new00);
tolua_function(tolua_S,"new_local",tolua_TestClass_TestClass_new00_local);
tolua_function(tolua_S,".call",tolua_TestClass_TestClass_new00_local);
tolua_function(tolua_S,"method1",tolua_TestClass_TestClass_method100);
tolua_function(tolua_S,"method2",tolua_TestClass_TestClass_method200);
tolua_function(tolua_S,"method3",tolua_TestClass_TestClass_method300);
tolua_endmodule(tolua_S);
tolua_endmodule(tolua_S);
return 1;
}
#if defined(LUA_VERSION_NUM) && LUA_VERSION_NUM >= 501
TOLUA_API int luaopen_TestClass (lua_State* tolua_S) {
return tolua_TestClass_open(tolua_S);
};
#endif
感谢您的回复,我编辑帖子以包含TestClass.cpp代码。 – Kinto 2011-04-06 13:00:22
我将lua_State *参数传递给构造函数的原因是因为我希望创建的对象将其作为属性存储,因此可以使用它来调用lua函数本身。在我意识到tolua ++生成的代码可能会在我的lua_State中传递之前,我提出了这个想法,因此我正在试验,看看我是否可以在没有我的诡计的情况下运行类似的代码来尝试隔离问题。 – Kinto 2011-04-06 13:04:02