返回一个带有LuaInterface的字符串 [英] Return a String with LuaInterface

问题描述

所以，我试图在C＃中将Lua实现为脚本语言。它很简单，真的，如果你使用它作为控制台应用程序的一部分。但我想要能够在XNA中创建一个游戏控制台。问题是Lua.DoString（）似乎返回一个控制台行，而不是一个字符串 - 如我所说，这是很好的控制台应用程序，但我想将它作为字符串添加到输出缓冲区，所以我可以显示它在游戏中，而不是在控制台窗口。如果这很困惑，我道歉，希望代码可以清除它。

So, I'm trying to implement Lua as a scripting language in C#. It's simple enough, really, if you use it as part of a console application. But I want to be able to create a game console within XNA. The problem is that Lua.DoString() seems to return a console line, rather than a string - which, as I said, is fine for console applications, but I want to add it to an output buffer as a string so I can display it in-game, rather than in a console window. I apologize if this is confusing - hopefully the code will clear it up.

using System;
using System.Collections.Generic;
using LuaInterface;

namespace LuaConsoleLibrary
{
    public class LuaConsole
    {
        private Lua lua;

        private bool isRunning = true;
        private string input;
        private List<string> outputBuffer;

        public bool IsRunning
        {
            get { return isRunning; }
        }

        public LuaConsole()
        {
            this.lua = lua;
        }

        public void Run()
        {
            int i = 0;
            while(isRunning)
            {
                outputBuffer.Add("> ");

                input = Console.ReadLine();
                outputBuffer.Add("");

                try
                {
                    lua.DoString(input);
                }
                catch(Exception e)
                {
                    outputBuffer.Add(e.Message);
                }
                finally
                {
                    outputBuffer.Add("");
                }
            }
        }
    }
}

$ b b

基本上，我很困惑为什么 lua.DoString（input）; 应该工作，而不是使用 Console.WriteLine （lua.DoString（input））; 。我甚至尝试了 outputBuffer.Add（lua.DoString（input）.ToString（））; ，这是ToString是有效的，应该在理论上工作。相反，它执行 lua.DoString ，然后抛出异常 - 对象引用未设置为对象的实例。除非我错了，对象是 Lua ，这使得 lua 是有效的对象引用。无论如何，看到这两个解决方案不工作，我想知道是否有人知道足够LuaInterface建议一个替代方法，以获得相同的结果。我本质上想要的效果 outputBuffer.Add（lua.DoString（input））; 。顺便说一下，我用来测试这个Lua命令是 print（test） - 也许 print 以某种方式返回控制台行而不是字符串，但我不能想到从Lua返回字符串的另一种方法。

Basically, I'm confused as to why lua.DoString(input); should work as opposed to having to use Console.WriteLine(lua.DoString(input));. I've even tried outputBuffer.Add(lua.DoString(input).ToString());, which, being that ToString is valid there, should work in theory. Instead it performs lua.DoString and then throws an exception - "Object reference not set to an instance of an object". Unless I'm mistaken, the object in question is Lua, which makes lua a valid object reference. Anyway, seeing as these two solutions don't work, I was wondering if anyone knows enough about LuaInterface to suggest an alternative way to get the same result. I essentially want something to the effect of outputBuffer.Add(lua.DoString(input));. By the way, the Lua command I've been using to test this is print("test") - maybe print is somehow returning a console line instead of a string, but I can't think of another way to return a string from Lua.

如果我的问题是rambling，我道歉或者解释不好 - 我试图尽可能简洁，但它是一个利基问题，我不知道如何解释它，真的。哦，我试过谷歌，我浏览了所有65左右的关于Stack Overflow的LuaInterface问题，所以我95％肯定我在提出这个问题之前做了我的尽职调查。 LuaInterface只是不知道一个工具，我猜。

I apologize if my problem is rambling or poorly explained - I tried to be as concise as possible, but it's kind of a niche issue and I don't know how else to explain it, really. Oh, and I did try Google, and I browsed all 65 or so LuaInterface questions on Stack Overflow, so I'm 95% sure I've done my due diligence before asking this question. LuaInterface is just not that well-known of a tool, I guess.

推荐答案

到对象的实例是C＃的说法某事是null，它不应该是。

Object reference not set to instance of an object is C#'s way of saying "something is null and it shouldn't be."

在这种情况下，很可能DoString返回null，因此null.ToString（）引发异常。你可以尝试 outputBuffer.Add（Convert.ToString（lua.DoString（input）[0]））如果你想转换为字符串不抛出null。

In this case, most likely DoString is returning null, so null.ToString() is raising the exception. You could try outputBuffer.Add(Convert.ToString(lua.DoString(input)[0])) if you want to convert to string without throwing on nulls.

我没有使用LuaInterface或者NLua，但我想要返回一个字符串，你实际上必须执行 return test作为您的Lua命令。

I haven't used either LuaInterface or NLua, but I'd guess that to return a string you'd actually have to execute return "test" as your Lua command.

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