Can I safely use object initializers inside using statements?

Question

I'm wondering if the use of object initializers inside using statements somehow prevents the correct disposal of the resource declared inside them, e.g.

using (Disposable resource = new Disposable() { Property = property })
{
   // ...
}

I've read that object initializers are nothing but synctatic sugar, which the compiler translates to something similar to the following code:

MyClass tmp = new MyClass(); 
tmp.Property1 = 1;
tmp.Property2 = 2;
actualObjectYouWantToInitialize = tmp;

Even if I may appear as a confused ignorant, I'd like to ask for clarifications. Does the fact that the initialized object is (as far as I understand) a pointer to another object (which is also a pointer, as far as I know), interfere with the disposal of the resource done by a using statement?

Answer 1

主要的（唯一的）危险是，如果设置Property失败（即引发异常），则resource 不会被设置为Disposed。

using (Disposable resource = new Disposable() { Property = property })
{
   // ...
}

通常using块内的例外是很好的-因为using语法是语法糖try .. finally。

这里的问题是，在有效Property = property执行时，您还没有“深入”该块。这与构造函数引发异常的情况本质上没有什么不同。using

在所有属性都设置好之后，将设置该finally块将要尝试执行的Dispose操作resource（但resource从未设置过）resource（如您的actualObjectYouWantToInitialize示例所示） 。

https://dotnetfiddle.net/vHeu2F演示了在实践中可能如何发生。请注意Dispose，即使有两个using块，也只记录一次。

using System;

namespace Bob
{
    public class Disposable : IDisposable
    {
        private int _property;

        public int Property { get => _property; set => throw new Exception(); }

        public void Dispose()
        {
            Console.WriteLine("Disposed");
        }
    }

    public class Program
    {
        public static void Main()
        {
            Console.WriteLine("1");
            using (var resource = new Disposable())
            {
                Console.WriteLine("2");
            }
            Console.WriteLine("3");


            using (var resource = new Disposable() { Property = 1 })
            {
                Console.WriteLine("4");

            }
            Console.WriteLine("5");
        }
    }
}

CA2000可能有助于检测此问题。