请问C＃编译器会自动处理IDisposable的对象？ [英] Does the C# compiler automatically dispose of IDisposable objects?

问题描述

假设我有一个方法公共静态矩形的DrawRectangle（矢量产地，矢量大小）返回类型的对象矩形：IDisposable的

Assuming I have a method public static Rectangle DrawRectangle(Vector origin, Vector size) which returns an object of type Rectangle : IDisposable

如果我只调用方法的DrawRectangle（产地，规格），但不分配返回值给一个变量 myRectangle =的DrawRectangle（出身，尺寸），将编译器会自动检测到，并调用的DrawRectangle（产地，规格）.Dispose（），还是我必须这样做我自己？

If I call only the method DrawRectangle(origin, size), but do not assign the return value to a variable myRectangle = DrawRectangle(origin, size), will the compiler automatically detect this and call DrawRectangle(origin, size).Dispose(), or do I have to do it myself?

推荐答案

有只有两种情况下我能想到的在这里编译器会自动调用Dispose;最明显的是：

There are only two scenarios I can think of where the compiler automatically calls dispose; the most obvious would be:

using(var obj = ... )
{
  // some code
}

这是一个明确的指示说末，无论是成功还是失败，如果 OBJ 非空，调用 obj.Dispose （）。基本上，它扩展为：

which is an explicit instruction to say "at the end, whether success or failure, if obj is non-null, call obj.Dispose()". Basically it expands to:

{
   var obj = ...
   try {
       // some code
   } finally {
       if(obj != null) obj.Dispose();   
   }
}

另外就是的foreach ，其中，由迭代器设置 - 虽然它变得有点复杂，因为的IEnumerator 未指定的IDisposable 是必需的（相比之下，的IEnumerator＆LT; T＆GT; 的确实指定），并在技术上的IEnumerable 甚至不要求的foreach ，但基本上是：

The other is foreach, where-by the iterator is disposed - although it gets a bit complicated, because IEnumerator doesn't specify that IDisposable is required (by contrast, IEnumerator<T> does specify that), and technically IEnumerable is not even required for foreach, but basically:

foreach(var item in sequence) {
   // some code
}

可能是pssed作为前$ P $（尽管该规范可以说是略有不同）：

could be expressed as (although the spec may say it slightly differently):

{
    var iter = sequence.GetEnumerator();
    using(iter as IDisposable)
    {
        while(iter.MoveNext())
        {   // note that before C# 5, "item" is declared *outside* the while
            var item = iter.Current;
            // some code
        }
    }
}

在所有其他情况下，配置资源的您的责任。

In all other cases, disposing resources is your responsibility.

如果您不能确保的Dispose（）被调用，那么什么都不会发生，直到GC最终收集的对象; 如果的有一个终结器（有没有要，而且通常不是），终结器将被调用 - 但是，这是不同的的Dispose（）。它的的可以的（根据每个类型的实现），最终会做同样的事情，的Dispose（）：但也可能不是。

If you don't ensure that Dispose() is called, then nothing will happen until GC eventually collects the object; if there is a finalizer (there doesn't have to be, and usually isn't), the finalizer will be invoked - but that is different to Dispose(). It may (depending on the per-type implementation) end up doing the same thing as Dispose(): but it may not.

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