c# - GOTO 在 using 块中，对象会被处理吗？

Question

我很不确定在块goto内使用。using

例如：

using(stream s = new stream("blah blah blah"));
{
    //do some stuff here

    if(someCondition) goto myLabel;
}

现在如果someCondition为真，代码执行将继续执行myLabel，但是，对象会被释放吗？

我在这里看到了一些关于这个主题的很好的问题，但他们都在谈论不同的事情。

Answer 1

是的。

---

但为什么不自己尝试呢？

void Main()
{
    using(new Test())
    {
        goto myLabel;
    }
myLabel:
    "End".Dump();
}
class Test:IDisposable
{
    public void Dispose()
    {
        "Disposed".Dump();
    }
}

结果：

处置
端

Answer 2

The using statement is essentially a try-finally block and a dispose pattern wrapped up in one simple statement.

using (Font font1 = new Font("Arial", 10.0f))
{
    //your code
}

Is equivalent to

Font font1 = new Font("Arial", 10.0f);
try
{
     //your code
}
finally
{
     //Font gets disposed here
}

Thus, any jump from the "try-block", be it throwing an exception, the use of goto (unclean!) &tc. will execute the Disposal of the object being used in that "finally" block..

Answer 3

let's try:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            int i = 0;
            using (var obj = new TestObj())
            {
                if (i == 0) goto Label;
            }
            Console.WriteLine("some code here");

        Label:
            Console.WriteLine("after label");

        Console.Read();
        }
    }

    class TestObj : IDisposable
    {
        public void Dispose()
        {
            Console.WriteLine("disposed");
        }
    }

}

Console output is : disposed after label

Dispose() execute before codes after the label .

Answer 4

using(Stream s = new Stream("blah blah blah"))
{    
    if(someCondition) goto myLabel;
}

等于

Stream s;
try
{
     s = new Stream("blah blah blah");
     if(someCondition) goto myLabel;
}
finally
{
  if (s != null)
    ((IDisposable)s).Dispose();
}

因此，只要您离开using块，该finally块就会发生，无论是什么让它退出。