luaL_dostring 在堆栈上什么都不放?

问题描述

我正在尝试学习 Lua 与 C++ 接口的基础知识，但遇到了一个问题.我想调用一个返回字符串的函数，然后在 C++ 端处理这个字符串，但是 luaL_dostring 似乎没有在 Lua 堆栈上放任何东西.

I'm trying to learn the basics of interfacing Lua with C++, but I've run into a problem. I want to call a function that returns a string, and then work with the string on the C++ side, but luaL_dostring seems to put nothing on the Lua stack.

即使是一个简单的测试似乎也不能正常工作:

Even a simple test doesn't seem to work properly:

lua_State* lua = lua_open();
luaL_openlibs(lua);

//Test dostring.
luaL_dostring(lua, "return 'derp'");

int top = lua_gettop(lua);
cout << "stack top is " <<top << endl;

//Next, test pushstring.
lua_pushstring(lua, "derp");

top = lua_gettop(lua);
cout << "stack top is " << top << endl;

输出:

stack top is 0
stack top is 1

有什么想法吗?

推荐答案

啊哈，发现问题了.根据 this page，在 Lua 5.1 中 luaL_dostring 忽略返回.我的代码可能适用于 Lua 5.2.

Aha, found the problem. According to this page, in Lua 5.1 luaL_dostring ignores returns. The code I had would probably work in Lua 5.2.

要更改功能，您应该使用:

To alter the functionality, you should use:

#undef luaL_dostring
#define luaL_dostring(L,s)  
    (luaL_loadstring(L, s) || lua_pcall(L, 0, LUA_MULTRET, 0))

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