使用lambdas代替IDisposable。

我从来没有对使用/IDisposable这个想法感到兴奋。问题是它要求调用者:

知道他们必须使用IDisposable 记住使用“using”。

我新的首选方法是使用工厂方法和lambda代替

假设我想用SqlConnection(应该用using包装的东西)做一些事情。通常你会这么做

using (Var conn = Factory.MakeConnection())
{
     conn.Query(....);
}

新方法

Factory.DoWithConnection((conn)=>
{
    conn.Query(...);
}

在第一种情况下，调用者不能简单地使用using语法。在第二种情况下，用户没有选择。没有创建SqlConnection对象的方法，调用者必须调用DoWithConnection。

DoWithConnection看起来像这样

void DoWithConnection(Action<SqlConnection> action)
{
   using (var conn = MakeConnection())
   {
       action(conn);
   }
}

MakeConnection现在是私有的

据我所知，强烈建议不要使用终结器/析构函数:

public ~MyClass() {
  //dont use this
}

大多数情况下，这是因为不知道何时或是否会调用它。处置方法是更好的，特别是如果你使用或直接处置。

使用是好的。使用它:)

我同意pm100的观点(我应该在之前的文章中明确地说明这一点)。

除非需要，否则永远不要在类中实现IDisposable。具体来说，大约有5次你需要/应该实现IDisposable:

Your class explicitly contains (i.e. not via inheritance) any managed resources which implement IDisposable and should be cleaned up once your class is no longer used. For example, if your class contains an instance of a Stream, DbCommand, DataTable, etc. Your class explicitly contains any managed resources which implement a Close() method - e.g. IDataReader, IDbConnection, etc. Note that some of these classes do implement IDisposable by having Dispose() as well as a Close() method. Your class explicitly contains an unmanaged resource - e.g. a COM object, pointers (yes, you can use pointers in managed C# but they must be declared in 'unsafe' blocks, etc. In the case of unmanaged resources, you should also make sure to call System.Runtime.InteropServices.Marshal.ReleaseComObject() on the RCW. Even though the RCW is, in theory, a managed wrapper, there is still reference counting going on under the covers. If your class subscribes to events using strong references. You need to unregister/detach yourself from the events. Always to make sure these are not null first before trying to unregister/detach them!. Your class contains any combination of the above...

对于使用COM对象并且必须使用Marshal.ReleaseComObject()，推荐的替代方法是使用System.Runtime.InteropServices.SafeHandle类。

BCL(基类库团队)在这里有一篇关于它的很好的博客文章http://blogs.msdn.com/bclteam/archive/2005/03/16/396900.aspx

一个非常重要的注意事项是，如果你正在使用WCF并清理资源，你几乎总是应该避免使用'using'块。有很多博客和MSDN上的文章都在解释为什么这是一个坏主意。我也在这里发布了关于它的帖子-不要在WCF代理中使用'using()'

Note that any IDisposable implementation should follow the below pattern (IMHO). I developed this pattern based on info from several excellent .NET "gods" the .NET Framework Design Guidelines (note that MSDN does not follow this for some reason!). The .NET Framework Design Guidelines were written by Krzysztof Cwalina (CLR Architect at the time) and Brad Abrams (I believe the CLR Program Manager at the time) and Bill Wagner ([Effective C#] and [More Effective C#] (just take a look for these on Amazon.com:

Note that you should NEVER implement a Finalizer unless your class directly contains (not inherits) UNmanaged resources. Once you implement a Finalizer in a class, even if it is never called, it is guaranteed to live for an extra collection. It is automatically placed on the Finalization Queue (which runs on a single thread). Also, one very important note...all code executed within a Finalizer (should you need to implement one) MUST be thread-safe AND exception-safe! BAD things will happen otherwise...(i.e. undetermined behavior and in the case of an exception, a fatal unrecoverable application crash).

我把模式放在一起(并为其编写了代码片段)如下:

#region IDisposable implementation

//TODO remember to make this class inherit from IDisposable -> $className$ : IDisposable

// Default initialization for a bool is 'false'
private bool IsDisposed { get; set; }

/// <summary>
/// Implementation of Dispose according to .NET Framework Design Guidelines.
/// </summary>
/// <remarks>Do not make this method virtual.
/// A derived class should not be able to override this method.
/// </remarks>
public void Dispose()
{
    Dispose( true );

    // This object will be cleaned up by the Dispose method.
    // Therefore, you should call GC.SupressFinalize to
    // take this object off the finalization queue 
    // and prevent finalization code for this object
    // from executing a second time.

    // Always use SuppressFinalize() in case a subclass
    // of this type implements a finalizer.
    GC.SuppressFinalize( this );
}

/// <summary>
/// Overloaded Implementation of Dispose.
/// </summary>
/// <param name="isDisposing"></param>
/// <remarks>
/// <para><list type="bulleted">Dispose(bool isDisposing) executes in two distinct scenarios.
/// <item>If <paramref name="isDisposing"/> equals true, the method has been called directly
/// or indirectly by a user's code. Managed and unmanaged resources
/// can be disposed.</item>
/// <item>If <paramref name="isDisposing"/> equals false, the method has been called by the 
/// runtime from inside the finalizer and you should not reference 
/// other objects. Only unmanaged resources can be disposed.</item></list></para>
/// </remarks>
protected virtual void Dispose( bool isDisposing )
{
    // TODO If you need thread safety, use a lock around these 
    // operations, as well as in your methods that use the resource.
    try
    {
        if( !this.IsDisposed )
        {
            if( isDisposing )
            {
                // TODO Release all managed resources here

                $end$
            }

            // TODO Release all unmanaged resources here



            // TODO explicitly set root references to null to expressly tell the GarbageCollector
            // that the resources have been disposed of and its ok to release the memory allocated for them.


        }
    }
    finally
    {
        // explicitly call the base class Dispose implementation
        base.Dispose( isDisposing );

        this.IsDisposed = true;
    }
}

//TODO Uncomment this code if this class will contain members which are UNmanaged
// 
///// <summary>Finalizer for $className$</summary>
///// <remarks>This finalizer will run only if the Dispose method does not get called.
///// It gives your base class the opportunity to finalize.
///// DO NOT provide finalizers in types derived from this class.
///// All code executed within a Finalizer MUST be thread-safe!</remarks>
//  ~$className$()
//  {
//     Dispose( false );
//  }
#endregion IDisposable implementation

下面是在派生类中实现IDisposable的代码。注意，您不需要在派生类的定义中显式地列出来自IDisposable的继承。

public DerivedClass : BaseClass, IDisposable (remove the IDisposable because it is inherited from BaseClass)


protected override void Dispose( bool isDisposing )
{
    try
    {
        if ( !this.IsDisposed )
        {
            if ( isDisposing )
            {
                // Release all managed resources here

            }
        }
    }
    finally
    {
        // explicitly call the base class Dispose implementation
        base.Dispose( isDisposing );
    }
}

我已经在我的博客上发布了这个实现:如何正确地实现Dispose模式

使用lambdas代替IDisposable。

我从来没有对使用/IDisposable这个想法感到兴奋。问题是它要求调用者:

知道他们必须使用IDisposable 记住使用“using”。

我新的首选方法是使用工厂方法和lambda代替

假设我想用SqlConnection(应该用using包装的东西)做一些事情。通常你会这么做

using (Var conn = Factory.MakeConnection())
{
     conn.Query(....);
}

新方法

Factory.DoWithConnection((conn)=>
{
    conn.Query(...);
}

在第一种情况下，调用者不能简单地使用using语法。在第二种情况下，用户没有选择。没有创建SqlConnection对象的方法，调用者必须调用DoWithConnection。

DoWithConnection看起来像这样

void DoWithConnection(Action<SqlConnection> action)
{
   using (var conn = MakeConnection())
   {
       action(conn);
   }
}

MakeConnection现在是私有的

using(NoGateway objNoGateway = new NoGateway())

等于

try
{
    NoGateway = new NoGateway();
}

finally
{
    NoGateway.Dispose();
}

在GC销毁对象时调用终结器。这可能与你离开方法时完全不同。Dispose of IDisposable在你离开using块后立即被调用。因此，这种模式通常是在您不再需要资源后立即使用using来释放它们。