对象初始化和处置财产时可以抛出异常 [英] Object initializer and Dispose when property can throw exception

问题描述

我有以下设置：

public class SomeClass
{
  private DirectoryEntry _root;
  private DirectorySearcher _searcher;

  public SomeClass()
  {
    _root = new DirectoryEntry("ldap://bla");
    _searcher = new DirectorySearcher(_root)
      {
        PageSize = int.MaxValue,
        SizeLimit = int.MaxValue
      }
  }
}

我用int.MaxValue的原因是因为在这种情况下，我知道我会超过默认值，但数量永远不会大得离谱，所以我很好关于这一点。

The reason I use int.MaxValue is because in this case I know I'll exceed the defaults, but the number will never be ridiculously large, so I'm fine about that point.

但是，如果我打开的代码分析和 Microsoft基本正确性规则的它抱怨：

But if I turn on Code Analysis and Microsoft Basic Correctness Rules it complains:

2警告CA2000：Microsoft.Reliability：在方法'SomeClass.SomeClass（） '对象'<> G_的 initLocal0'是不是沿着所有的异常路径处理。呼叫System.IDisposable.Dispose的对象。'<>先按g 的_initLocal0'之前对它的所有引用超出范围

Warning 2 CA2000 : Microsoft.Reliability : In method 'SomeClass.SomeClass()', object '<>g_initLocal0' is not disposed along all exception paths. Call System.IDisposable.Dispose on object '<>g_initLocal0' before all references to it are out of scope.

它的问题是，每页和的sizeLimit可以抛出异常，如果发生在 G__initLocal0 对象没有得到处理（即使 _searcher 并获得释放）。他们可以抛出唯一的例外是，如果你将它们分配给一个负数，不能在这里发生，但它仍然抱怨。

It's problem is that PageSize and SizeLimit can throw exceptions, and if that happens the G__initLocal0 object doesn't get disposed (even if _searcher does get disposed). The exception they can throw is if you assign them to a negative number, which can't happen here but it still complains.

接下来，我设置对象intitializer之外的属性与常规赋值语句，但随后ReSharper的笙歌告诉我，我应该使用初始化程序。我可以抑制ReSharper的，但我喜欢图把事情不增加抑制工作的一种方式。

Next I set the properties outside an object intitializer with regular assignment statements, but then ReSharper complains telling me that I should be using Initializer. I could suppress ReSharper, but I like to figure a way of getting things to work without adding suppressing.

所以我想我不得不捕获错误，我不就像在我的构造函数如果有可能捕获错误，所以我创建了一个叫做搜索器属性是这样的：

So I figured I had to catch the error and I don't like catch errors in my constructors if possible, so I created a property called Searcher like this:

private DirectorySearcher _searcher;
public DirectorySearcher Searcher
{
  get
  {
    if (_searcher != null) return _searcher;
    var searcher = new DirectorySearcher();
    try
    {
      searcher.PageSize = int.MaxValue;
      searcher.SizeLimit = int.MaxValue;
      _searcher = searcher;
    }
    catch
    {
      searcher.PageSize = 1000;
      searcher.SizeLimit = 1000;
    }
    finally
    {
      searcher.Dispose();
    }
    return _searcher;
  }
}

现在代码分析，一切都是幸福的，但我不是很满意的解决方案可言。

Now Code Analysis and everything is happy, but I'm not happy with the solution at all.

任何提示？

推荐答案

你正在做的事情现在可能让所有人都满意的方式，但你作为它不会工作。在返回处置的DirectorySearcher 在搜索器属性。

The way you are doing things now might make everyone happy but you as it wont work. You are returning a disposed DirectorySearcher in your Searcher property.

我只是做的：

public SomeClass()
{
    _root = new DirectoryEntry("ldap://bla");

    try
    {
        _searcher = new DirectorySearcher(_root);
        _searcher.PageSize = 1000;
        _searcher.SizeLimit = 1000;
    }
    catch
    {
         if (_searcher != null)
         {
             _searcher.Dispose();
         }

         throw;
    }

}

}

我看不出什么错在构造函数使用的try-catch 块。

I don't see whats wrong in using try-catch blocks in constructors.

我不推荐的构建的IDisposable 对象，如果一个属性初始化抛出无法处理它们通常是当财产初始化语法。

I wouldn't recommed the property initializer syntax when constructing IDisposable objects as you cannot dispose them normally if a property initialization throws.

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