为嵌入式Lua脚本设置“环境” [英] Setting up an 'environment' for an embedded Lua Script

问题描述

我在一个C ++应用程序中嵌入了一个Lua解释器。

I am embedding a Lua interpreter in a C++ application.

我想为运行脚本设置一个环境，使某些变量脚本。

I want to setup an 'environment' for running scripts, such that certain variables are made available to all scripts.

例如，我想将READ ONLY对象Foo和FooBar暴露给脚本，以便Foo和FooBar可用于所有正在运行的脚本。

For example, I want to expose READ ONLY objects Foo and FooBar to scripts, such that Foo and FooBar are available to all running scripts.

有谁知道我该怎么做？

Does anyone know how I can do this?. A snippet to show how to so this would be very useful.

推荐答案

我没有听说过Lua中的只读变量但是你可以通过调用一个函数调用来阻止修改。

I haven't heard of read-only variables in Lua but you can prevent modification by making the environment available via a function call instead.

如果C ++应用程序很大，你可能需要使用一个工具生成一个接口你可以从Lua打电话。我过去用了tolua ++运气：

If the C++ application is large, you will probably want to use a tool to generate an interface you can call from Lua. I have used tolua++ in the past with some luck:

假设 demo.hpp 是C ++的头文件应用程序：

Suppose demo.hpp is a header file of the C++ application:

#ifndef SO_DEMO_HPP
#define SO_DEMO_HPP

namespace demo
{
    class Foo
    {
        double x;

    public:
        Foo(double x) : x(x) {}
        double getX() const { return x; }
    };

    Foo* getFoo();
}

#endif

实施 demo :: getFoo（）在 demo.cpp 。

demo.pkg 列出了应该从Lua调用的内容：

demo.pkg lists the things that should be callable from Lua:

$#include "demo.hpp"

namespace demo
{
    class Foo
    {
        double getX() const;
    };

    Foo* getFoo();
}

生成 demo_stub.cpp 和 demo_stub.hpp 包含我们的Lua模块的文件：

Generate demo_stub.cpp and demo_stub.hpp files containing our Lua module:

$ tolua++5.1 -o demo_stub.cpp -H demo_stub.hpp demo.pkg

main.cpp 是一个Lua解释器，它加载 demo 模块：

main.cpp is a Lua interpreter that loads the demo module:

#include "demo.hpp"

extern "C" {
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#include <tolua++.h>
}
#include "demo_stub.hpp"

int main()
{
    lua_State *L = lua_open();

    luaL_openlibs(L);
    tolua_demo_open(L);

    if (luaL_dofile(L, NULL) != 0)
        fprintf(stderr, "%s\n", lua_tostring(L, -1));

    lua_close(L);
    return 0;
}

tolua_demo_open（）函数由tolua ++生成，并在 demo_stub.hpp 中声明。

The tolua_demo_open() function was generated by tolua++ and is declared in demo_stub.hpp.

创建一个名为 demo ：

$ g++ -I/usr/include/lua5.1 demo.cpp demo_stub.cpp main.cpp -ltolua++5.1 -llua5.1 -o demo

demo.lua 脚本

print("Hello, world!")
print(tolua.type(demo.getFoo()))
print(demo.getFoo():getX())

并将脚本提供给解释器：

and feed the script to the interpreter:

$ ./demo < demo.lua
Hello, world!
demo::Foo
42

这篇关于为嵌入式Lua脚本设置“环境”的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！