为嵌入式 Lua 重定向/重新定义 print()

问题描述

我在我的 C++ 应用程序中嵌入了 Lua.我想重定向打印语句(或者可能只是重新定义打印函数?)，以便我可以在其他地方显示计算的表达式.

I have embedded Lua in my C++ application. I want to redirect print statements (or maybe simply redefine the print function?), so that I can display the evaluated expression somewhere else.

执行此操作的最佳方法是什么:重定向或重新定义 print() 函数?

What is the best way to do this: redirect or redefining the print() function?

任何显示如何执行此操作的代码段/指向代码段的指针都将不胜感激.

Any snippets/pointers to snippets that show how to do this would be much appreciated.

推荐答案

你可以在C中重新定义print语句:

You can redefine the print statement in C:

static int l_my_print(lua_State* L) {
    int nargs = lua_gettop(L);

    for (int i=1; i <= nargs; i++) {
        if (lua_isstring(L, i)) {
            /* Pop the next arg using lua_tostring(L, i) and do your print */
        }
        else {
        /* Do something with non-strings if you like */
        }
    }

    return 0;
}

然后在全局表中注册:

static const struct luaL_Reg printlib [] = {
  {"print", l_my_print},
  {NULL, NULL} /* end of array */
};

extern int luaopen_luamylib(lua_State *L)
{
  lua_getglobal(L, "_G");
  // luaL_register(L, NULL, printlib); // for Lua versions < 5.2
  luaL_setfuncs(L, printlib, 0);  // for Lua versions 5.2 or greater
  lua_pop(L, 1);
}

由于您使用的是 C++，因此您需要使用extern "C"" 来包含您的文件

Since you are using C++ you'll need to include your file using 'extern "C"'

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