如何在.NET 2.0的使用块中捕获异常？ [英] How to Catch an exception in a using block with .NET 2.0?

问题描述

当我有一个实现IDisposable的对象时，我试图越来越多地利用使用块，但是我还没有想到的是如何捕获一个异常，就像我在一个正常的try / catch / finally ...任何代码示例来指向我正确的方向？

编辑：问题在阅读回复后被修改。它是如何使用.NET 2.0在使用块中抛出异常？但我实际上正在寻找一种在使用块中捕获这些异常的方法。

---

我正在寻找更多的细节在一个使用块中滚动我自己的捕获块。

编辑：我想避免的是不得不使用try / catch / finally在我的使用块像@Blair显示。但是也许这是一个非问题...

编辑：@Blair，这正是我正在寻找的，谢谢详细的回复！

解决方案

我真的不明白这个问题 - 你通常会抛出异常。
如果 MyThing 实现 IDisposable ，那么：

  using（MyThing thing = new MyThing（））
 {
 ... 
 throw new ApplicationException（oops）; 
} 
  

和 thing.Dispose

  try 
 {
 ... 
 using（MyThing thing = new MyThing（））
 {
 ... 
} 
 ... 
 } 
 catch（异常e）
 {
 .... 
} 
终于
 {
 .... 
 
  

（或者将try / catch / finally放在使用中）：

  using（MyThing thing = new MyThing（））
 {
 ... 
 try 
 { 
 ... 
} 
 catch（异常e）
 {
 .... 
} 
 finally 
 {
 .... 
} 
 ... 
} // thing.Dispose现在调用
  

或者您可以使用展开，并显式调用 Dispose code> finally block as @Quarrelsome演示，添加任何额外的异常处理或-recovery代码，您需要在 finally （或 catch ）。

编辑：回应到@Toran Billups，如果您需要处理异常，除非确保调用 Dispose 方法，否则您必须使用使用和 try / catch / finally 或使用展开 - 我不认为有其他方法来完成你想要的。

I'm trying to leverage the using block more and more these days when I have an object that implements IDisposable but one thing I have not figured out is how to catch an exception as I would in a normal try/catch/finally ... any code samples to point me in the right direction?

Edit: The question was modified after reading through the replies. It was "How to Throw an exception in a using block with .NET 2.0?" but I was actually looking for a way to catch these exceptions inside a using block.

---

I'm looking for more detail on rolling my own catching block inside a using block.

Edit: What I wanted to avoid is having to use a try/catch/finally inside my using block like @Blair showed. But maybe this is a non issue...

Edit: @Blair, this is exactly what I was looking for, thanks for the detailed reply!

解决方案

I don't really understand the question - you throw an exception as you normally would. If MyThing implements IDisposable, then:

using ( MyThing thing = new MyThing() )
{
    ...
    throw new ApplicationException("oops");
}

And thing.Dispose will be called as you leave the block, as the exception's thrown. If you want to combine a try/catch/finally and a using, you can either nest them:

try
{
    ...
    using ( MyThing thing = new MyThing() )
    {
        ...
    }
    ...
}
catch ( Exception e )
{
    ....
}
finally
{
    ....
}    

(Or put the try/catch/finally in the using):

using ( MyThing thing = new MyThing() )
{
    ...
    try
    {
        ...
    }
    catch ( Exception e )
    {
        ....
    }
    finally
    {
        ....
    }    
    ...
} // thing.Dispose is called now

Or you can unroll the using and explicitly call Dispose in the finally block as @Quarrelsome demonstrated, adding any extra exception-handling or -recovery code that you need in the finally (or in the catch).

EDIT: In response to @Toran Billups, if you need to process exceptions aside from ensuring that your Dispose method is called, you'll either have to use a using and try/catch/finally or unroll the using - I don't thinks there's any other way to accomplish what you want.

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