该处置实现IDisposable成员 [英] Disposing the members that implement IDisposable

问题描述

在我的Dispose方法（如下面的那个），每次我想打电话给someObj.Dispose（）我也有someObj中！= NULL检查。

In my Dispose methods (like the one below), everytime i want to call someObj.Dispose() i also have a check for someObj!=null.

那是因为我的一部分不好的设计？
是其确定所有成员（实现IDisposable接口）中的对象正在使用的处置被称为无需NullReference异常的风险更清洁的方式？

Is that because of bad design on my part? Is their a cleaner way to ascertain that Dispose of all the members (implementing IDisposable) being used in an object is called without having a risk of NullReference exception ?

protected void Dispose(bool disposing)
        {
            if (disposing)
            {
               if (_splitTradePopupManager != null)
                {
                    _splitTradePopupManager.Dispose();
                }
             }
        }

感谢您的关注。

Thanks for your interest.

推荐答案

也许别人可以附和这一点，但我不个人认为这是一个设计缺陷 - 只有最安全的方式做到这一点。

Maybe someone else can chime in on this, but I don't personally think it's a design flaw -- just the safest way to do it.

这是说，没有什么阻止你从包装你的空检查和处置呼叫的简便方法：

That said, nothing's stopping you from wrapping your null check and Dispose call in a convenient method:

private void DisposeMember(IDisposable member)
{
    if (member != null)
        member.Dispose();
}

那么你的的Dispose 方法可能看起来有点清洁：

Then your Dispose method could look a bit cleaner:

protected void Dispose(bool disposing)
{
    if (disposing)
    {
        DisposeMember(_splitTradePopupManager);
        DisposeMember(_disposableMember2);
        DisposeMember(_disposableMember3);
    }
}

作为额外的奖励，这也解决了潜在的竞争条件在原来的代码。如果在多线程上下文中运行，在如果（_field！= NULL）_field.Dispose（）可导致的NullReferenceException 在 _field 是检查和处置（罕见，但有可能）之间设置为空。通过 _field 作为参数的方法，如 DisposeMember 复制参考方法的局部变量，消除这种可能，不太可能，因为它是。

As an added bonus, this also resolves a potential race condition in your original code. If running in a multithreaded context, the if (_field != null) _field.Dispose() pattern can result in a NullReferenceException when _field is set to null between the check and the disposal (rare, but possible). Passing _field as an argument to a method such as DisposeMember copies the reference to a local variable in the method, eliminating this possibility, unlikely as it is.

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