有关 Lua 调用 C++ 编译动态库程序

主要目标

希望能够将 cpp 文件编译成动态库, 以 lua 作为主要运行逻辑(main 函数)

希望解决的问题

刚入门 Lua 不太明白，若编译了一个 cpp 文件里包含了一个 Worker 对象，Lua 中如何调用生成这个对象并根据公有函数对私有变量进行操作。
查找到的一些示例代码，大多是将 main 逻辑放在 cpp 文件里，生成元表作为全局变量传入 Lua 脚本进行操作。但是将 Lua 作为程序运行入口，C++ 库作为辅助函数，又该如何操作。
Lua 调试工具各位 Lua 大佬能否介绍一下，或者推荐一些调试方法，lua 的 debug 调试使用我还是有点懵。

自身尝试代码

稍微有点多，感谢耐心观看

classstudy.h

#pragma once
extern "C" {
    #include "lua.h"
    #include "lualib.h"
    #include "lauxlib.h"
}

#include <string>

class Worker{
    public:
        Worker();
        ~Worker();

        int SetName(std::string &name);
        int SetAge(int &age);
        int SetHight(float &hight);

        std::string GetName();
        int GetAge();
        float GetHight();
    private:
        std::string name;
        int age;
        float hight;
};

extern "C" int luaopen_cstudy(lua_State *L);

classstudy.cpp

#include "classstudy.h"

#include <iostream>


/*
Class Worker 的函数定义省略
*/

static int CreateNewWorker(lua_State *L){
    //ligth_userdata
    // int n = luaL_checkany(L, 1);
    Worker **w1 = (Worker**)lua_newuserdata(L, sizeof(Worker*));
    *w1 = new Worker();
    if(luaL_getmetatable(L, "WorkerClass") == false){
        printf("getmetatable nil\n");
    }
    lua_setmetatable(L, -2);
    return 1;
}

static int SetWorkerName(lua_State *L){

    luaL_checktype(L, -1, LUA_TSTRING);
    std::string var_name = lua_tostring(L, -1);
    printf("%s\n", var_name.c_str());

    Worker **w1 = (Worker**)lua_newuserdata(L, sizeof(Worker*));
    luaL_argcheck(L, w1 != NULL, 1, "invalid user data");
    (*w1)->SetName(var_name);

    return 0;
}

static int SetWorkerAge(lua_State *L){

	luaL_checktype(L, -1, LUA_TNUMBER);
    int var_age = lua_tointeger(L, -1);
    Worker **w1 = (Worker**)lua_newuserdata(L, sizeof(Worker*));
    luaL_argcheck(L, w1 != NULL, 1, "invalid user data");
    (*w1)->SetAge(var_age);
    
    return 0;
}

static int SetWorkerHight(lua_State *L){

    luaL_checktype(L, -1, LUA_TNUMBER);
    float var_hight = lua_tonumber(L, -1);
    Worker **w1 = (Worker**)lua_newuserdata(L, sizeof(Worker*));
    luaL_argcheck(L, w1 != NULL, 1, "invalid user data");
    (*w1)->SetHight(var_hight);

    return 0;
}

static int GetWorkerInfo(lua_State *L){

    Worker **w1 = (Worker**)lua_newuserdata(L, sizeof(Worker*));
    luaL_argcheck(L, w1 != NULL, 1, "invalid user data");
    printf("Name: %s\n", ((*w1)->GetName()).c_str());
    printf("Age: %d\n", (*w1)->GetAge());
    printf("Hight: %f\n", (*w1)->GetHight());
    return 0;
}

static int DestoryInfo(lua_State* L)
{
    // 释放对象
    delete *(Worker**)lua_topointer(L, 1);
    return 0;
}

const static luaL_Reg mylib[] = {
    // {"NewWorker", CreateNewWorker},
    {"SetName", SetWorkerName},
    {"SetAge", SetWorkerAge},
    {"SetHight", SetWorkerHight},
    {"PrintInfo", GetWorkerInfo},
    {NULL,NULL}
};

int luaopen_cstudy(lua_State *L){
    
    // C\++对象     = 私有数据 + 类（公共数据 + 公共方法）  
    // Lua Table  = 私有数据 + 元表（元数据 + 元函数）

    //  luaL_newlib(L, mylib);
    lua_pushcfunction(L, CreateNewWorker);    // 注册用于创建类的全局函数
    lua_setglobal(L,  "CWorker");
    luaL_newmetatable(L, "WorkerClass");
    
    // 设置自身
    lua_pushstring(L, "__gc");
    lua_pushcfunction(L, DestoryInfo);
    lua_settable(L, -3);
    
    // 设置元表
    lua_pushstring(L, "__index"); // 设置元表为自己
    lua_pushvalue(L, -2);
    lua_settable(L, -3);

    lua_pushstring(L, "SetName");
    lua_pushcfunction(L, SetWorkerName);
    lua_settable(L, -3);

    lua_pushstring(L, "SetAge");
    lua_pushcfunction(L, SetWorkerAge);
    lua_settable(L, -3);

    lua_pushstring(L, "SetHight");
    lua_pushcfunction(L, SetWorkerHight);
    lua_settable(L, -3);

    lua_pushstring(L, "PrintInfo");
    lua_pushcfunction(L, GetWorkerInfo);
    lua_settable(L, -3);
    // lua_pop(L, 1);

    return 1;
}

classstudy.lua

local csl = require("cstudy")
local Worker = CWorker()
print(debug.getregistry())

Worker.SetName("hello")
Worker.PrintInfo()
-- csl.SetAge(23)
-- csl:SetHight(180.0)
-- csl:PrintInfo()

anytk

2022-01-06 11:32:58 +08:00

元表是对象，也就是你的 worker 的元表，包含对象的方法，在方法中检查第一个参数为对应元表名的 userdata, 其他为参数。
模块本身只提供创造对象的方法和必要全局参数。
参考：

```c
#include <lua.h>
#include <lauxlib.h>

static int xxx_read(lua_State *L)
{
struct XXX **xxx = luaL_checkudata(L, 1, "xxx.xxx");
// ...
}

static int xxx_write(lua_State *L)
{
struct XXX **xxx = luaL_checkudata(L, 1, "xxx.xxx");
// ...
}

static int xxx_close(lua_State *L)
{
struct XXX **xxx = luaL_checkudata(L, 1, "xxx.xxx");
if (*xxx) {
// ...
}
return 0;
}

static luaL_Reg XXX_METHODS[] = {
{ "read", xxx_read },
{ "write", xxx_write },
{ "close", xxx_close },
{ "__gc", xxx_close },
{ NULL, NULL },
};

static int xxx_new(lua_State *L)
{
lua_Integer type = luaL_checkinteger(L, 1);
const char *url = luaL_checkstring(L, 2);

int err = 0;
struct XXX *xxx = create_xxx(...);
if (!xxx) {
lua_pushnil(L);
return 1;
} else {
struct XXX **udata = lua_newuserdata(L, sizeof(struct XXX *));
*udata = NULL;
luaL_setmetatable(L, "xxx.xxx");
*udata = xxx;
return 1;
}
}

static luaL_Reg XXX_LIBS[] = {
{ "new", xxx_new },
{ NULL, NULL },
};

int luaopen_xxx.xxx(lua_State *L)
{
luaL_newmetatable(L, "xxx.xxx");
lua_pushvalue(L, -1);
lua_setfield(L, -2, "__index");
luaL_setfuncs(L, XXX_METHODS, 0);
lua_pop(L, 1);
luaL_newlib(L, XXX_LIBS);
return 1;
}

```