Unity3D 中的 C# 匿名函数作用域 [英] C# Anonymous Function Scope in Unity3D
问题描述
我在 Unity3D 中制作模拟项目时遇到了这种令人费解的行为.
I came across this puzzling behavior while making a simulation project in Unity3D.
基本上,我使用被循环的变量在循环中创建匿名函数,并将所有这些函数添加到队列中进行处理.
Unity3D Monobehavior 中奇怪的情况是它们只在最后一个循环变量上调用.
Basically, I was creating anonymous functions in a loop using the variable being looped, and add all these functions to a queue for processing.
The curious case in Unity3D Monobehavior is that they are only called on the last looped variable.
using UnityEngine;
using System.Collections;
using System.Collections.Generic;
using System;
public class TestDist : MonoBehaviour {
int counter = 0;
// Use this for initialization
void Start () {
List<LOL> lols = new List<LOL>();
lols.Add(new LOL(1));
lols.Add(new LOL(2));
lols.Add(new LOL(3));
List<Func<int>> fs = new List<Func<int>>();
foreach (LOL l in lols)
{
//****** Critical Section *********
Func<int> func = () =>
{
Debug.Log(l.ID); //Prints "3" 3 times instead of
return 0; // "1", "2", "3"
};
//****** Critical Section *********
fs.Add(func);
}
foreach (Func<int> f in fs)
{
f();
}
}
// Update is called once per frame
void Update () {
}
}
class LOL
{
public long ID;
public LOL(long id)
{
ID = id;
}
}
代码在普通的 Visual Studio 控制台应用程序中运行良好,但在 Unity3D 上失败.(版本 5.0)通过打印最后一个值(3")3 次而不是 1,2,3.
我尝试了各种方法来规避,但以下方法没有明显原因:将临界区更改为以下块可以解决问题:
The code works good in plain Visual Studio Console application, but fails on Unity3D. (Version 5.0) by printing the last value ("3") 3 times instead of 1,2,3.
I tried various methods to circumvent and the following worked for no apparent reason :
Changing the Critical Section to the following block solves the issue:
LOL another = l;
Func<int> func = () =>
{
Debug.Log(another.ID);
return 0;
};
如果有人能回答我会很高兴(Unity Bug Fix Team 似乎并不关心)
Will be delighted if someone can answer (Unity Bug Fix Team does not seem to care)
推荐答案
您正面临关闭的问题.
看到这个问题:什么是 C# 中的闭包"?
试试这个.它只是相同,但不完全相同,因为您在循环中声明了一个新"lol
:
Try this instead. Its merely the same, but not completely since you declare a "new" lol
in your loop :
for( int index = 0 ; index < lols.Count ; ++index )
{
Lol l = lols[index];
Func<int> func = () =>
{
Debug.Log(l.ID);
return 0;
};
fs.Add(func);
}
如果它不起作用,请尝试:
If it does not work, try :
foreach (LOL l in lols)
{
fs.Add(GetFunction(l.ID));
}
// ...
private Func<int> GetFunction( int identifier)
{
Func<int> func = () =>
{
Debug.Log(identifier);
return 0;
};
return func ;
}
我对关闭感到不舒服,我必须承认.
I does not feel comfortable with closure, I must admit.
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