For the equivalent mechanism in C++ (the destructor), the advice is that [it should usually not throw any exceptions][1]. This is mainly because by doing so you might terminate your process, which is only very rarely a good strategy.

In the equivalent scenario in .NET ...

1. A first exception is thrown
2. A finally block is executed as a result of the first exception
3. The finally block calls a Dispose() method
4. The Dispose() method throws a second exception

... your process does not terminate immediately. However, you lose information because .NET unceremoneously replaces the first exception with the second one. A catch block somewhere up the call stack will therefore never see the first exception. However, one is usually more interested in the first exception because that normally gives better clues as to why things started to go wrong.

Since .NET lacks a mechanism to detect whether code is being executed while an exception is pending, it seems there are really only two choices how IDisposable can be implemented:

- Always swallow all exceptions that occur inside Dispose(). Not good as you might also end up swallowing OutOfMemoryException, ExecutionEngineException, etc. which I&#39;d usually rather let tear down the process when they occur without another exception already pending.
- Let all exceptions propagate out of Dispose(). Not good as you might lose information about the root cause of a problem, see above.

So, which is the lesser of the two evils? Is there a better way?

**EDIT**: To clarify, I&#39;m not talking about actively throwing exceptions from Dispose() or not, I&#39;m talking about letting exceptions thrown by methods called by Dispose() propagate out of Dispose() or not, for example:

    using System;
    using System.Net.Sockets;

    public sealed class NntpClient : IDisposable
    {
        private TcpClient tcpClient;

        public NntpClient(string hostname, int port)
        {
            this.tcpClient = new TcpClient(hostname, port);
        }

        public void Dispose()
        {
            // Should we implement like this or leave away the try-catch?
            try
            {
                this.tcpClient.Close(); // Let&#39;s assume that this might throw
            }
            catch
            {
            }
        }
    }

  [1]: http://www.parashift.com/c++-faq-lite/exceptions.html#faq-17.3


Should you implement IDisposable.Dispose() so that it never throws?

I am using the [`System.Net.Http.HttpClient`][1] to do some client-side HTTP communication. I&#39;ve got all of the HTTP in one spot, abstracted away from the rest of the code. In one instance I want to read the response content as a stream, but the consumer of the stream is well insulated from where the HTTP communication happens and the stream is opened. In the spot responsible for HTTP communication I am disposing of all of the `HttpClient` stuff.

This unit test will fail at `Assert.IsTrue(stream.CanRead)`:

    [TestMethod]
    public async Task DebugStreamedContent()
    {
        Stream stream = null; // in real life the consumer of the stream is far away 
        var client = new HttpClient();        
        client.BaseAddress = new Uri(&quot;https://www.google.com/&quot;, UriKind.Absolute);
        
        using (var request = new HttpRequestMessage(HttpMethod.Get, &quot;/&quot;))
        using (var response = await client.SendAsync(request))
        {
            response.EnsureSuccessStatusCode();
            //here I would return the stream to the caller
            stream = await response.Content.ReadAsStreamAsync();
        }
        
        Assert.IsTrue(stream.CanRead); // FAIL if response is disposed so is the stream
    }

I typically try to dispose of anything `IDisposable` at the earliest possible convenience but in this case, disposing the `HttpResponseMessage` also disposes the `Stream` returned from `ReadAsStreamAsync`.

So it seems like the calling code needs to know about and take ownership of the response message as well as the stream, or I leave the response message undisposed and let the finalizer deal with it. Neither option feels right. 

[This answer][2] talks about not disposing the `HttpClient`. How about the `HttpRequestMessage` and/or `HttpResponseMessage`?

Am I missing something? I am hoping to keep the consuming code ignorant of HTTP  but leaving all these undisposed objects around goes against year of habit!


  [1]: http://msdn.microsoft.com/en-us/library/system.net.http.httpclient(v=vs.118).aspx
  [2]: https://stackoverflow.com/questions/15705092/do-httpclient-and-httpclienthandler-have-to-be-disposed

When or if to Dispose HttpResponseMessage when calling ReadAsStreamAsync?

I have a class that handles events from a WinForms control. Based on what the user is doing, I am deferencing one instance of the class and creating a new one to handle the same event. I need to unsubscribe the old instance from the event first - easy enough. I&#39;d like to do this in a non-proprietary manner if possible, and it seems like this is a job for IDisposable. However, most documentation recommends IDisposable only when using unmanaged resources, which does not apply here.

If I implement IDisposable and unsubscribe from the event in Dispose(), am I perverting its intention? Should I instead provide an Unsubscribe() function and call that?


----------


**Edit:** Here&#39;s some dummy code that kind of shows what I&#39;m doing (using IDisposable). My actual implementation is related to some proprietary data binding (long story).

    class EventListener : IDisposable
    {
        private TextBox m_textBox;

        public EventListener(TextBox textBox)
        {
            m_textBox = textBox;
            textBox.TextChanged += new EventHandler(textBox_TextChanged);
        }

        void textBox_TextChanged(object sender, EventArgs e)
        {
            // do something
        }

        public void Dispose()
        {
            m_textBox.TextChanged -= new EventHandler(textBox_TextChanged);
        }
    }

    class MyClass
    {
        EventListener m_eventListener = null;
        TextBox m_textBox = new TextBox();

        void SetEventListener()
        {
            if (m_eventListener != null) m_eventListener.Dispose();
            m_eventListener = new EventListener(m_textBox);
        }
    }

In the actual code, the &quot;EventListener&quot; class is more involved, and each instance is uniquely significant. I use these in a collection, and create/destroy them as the user clicks around.


----------
**Conclusion**

I&#39;m accepting [gbjbaanb&#39;s answer][1], at least for now. I feel that the benefit of using a familiar interface outweighs any possible downside of using it where no unmanaged code is involved (how would a user of this object even know that?).

If anyone disagrees - please post/comment/edit. If a better argument can be made against IDisposable, then I&#39;ll change the accepted answer.


  [1]: https://stackoverflow.com/questions/452281/using-idisposable-to-unsubscribe-events#452321

Using IDisposable to unsubscribe events

I&#39;ve written my own custom data layer to persist to a specific file and I&#39;ve abstracted it with a custom DataContext pattern.

This is all based on the .NET 2.0 Framework (given constraints for the target server), so even though some of it might look like LINQ-to-SQL, its not! I&#39;ve just implemented a similar data pattern.


See example below for example of a situation that I cannot yet explain.

To get all instances of `Animal` - I do this and it works fine
    
    public static IEnumerable&lt;Animal&gt; GetAllAnimals() {
            AnimalDataContext dataContext = new AnimalDataContext();
                return dataContext.GetAllAnimals();
    }

And the implementation of the `GetAllAnimals()` method in the `AnimalDataContext` below

    public IEnumerable&lt;Animal&gt; GetAllAnimals() {
            foreach (var animalName in AnimalXmlReader.GetNames())
            {
                yield return GetAnimal(animalName);
            }
    }

The `AnimalDataContext` implements `IDisposable` because I&#39;ve got an `XmlTextReader` in there and I want to make sure it gets cleaned up quickly.  

Now if I wrap the first call inside a using statement like so

    public static IEnumerable&lt;Animal&gt; GetAllAnimals() {
            using(AnimalDataContext dataContext = new AnimalDataContext()) {
                return dataContext.GetAllAnimals();
            }
    }

and put a break-point at the first line of the `AnimalDataContext.GetAllAnimals()` method and another break-point at the first line in the `AnimalDataContext.Dispose()` method, and execute...

**the `Dispose()` method is called FIRST so that `AnimalXmlReader.GetNames()` gives *&quot;object reference not set to instance of object&quot;* exception because `AnimalXmlReader` has been set to `null` in the `Dispose()` ???**

Any ideas? I have a hunch that its related to `yield return` not being allowed to be called inside a try-catch block, which `using` effectively represents, once compiled... 



yield return statement inside a using() { } block Disposes before executing

Let&#39;s say I have the following WCF implementation:

    public Stream Download(string path)
    {
        FileStream stream = new FileStream(path, FileMode.Open, FileAccess.Read);
        return stream;
    }

Who&#39;s responsible for disposing the returned value? After all, a network failure might occur, hence the consumer might not be able to dispose it.

Stream as a return value in WCF - who disposes it?

When implementing IDisposable, I undertand that every method that shouldn&#39;t be called after the object&#39;s been disposed should throw the `ObjectDisposedException`.  But what is the standard for the name object that should be passed to the exception&#39;s constructor?

What should be passed as the objectName when throwing an ObjectDisposedException?

Should implementations of `IDisposable` make `Dispose()` safe to call multiple times? Or the opposite? What approach to most .NET Framework classes take?

Specifically, is it safe to call `System.Data.Linq.DataContext.Dispose()` multiple times?

The reason I ask is because I am wondering if this extra protection is necessary:

    public override void Dispose(bool disposing)
    {
        // Extra protection...
        if (this.obj != null)
        {
            this.obj.Dispose();
            this.obj = null;
        }

        // Versus simply...
        this.obj.Dispose();

        base.Dispose(disposing);
    }

when disposing `IDisposable` members of a class, or whether I should just call `this.obj.Dispose()` without concern for whether it has been previously called.

Should IDisposable.Dispose() be made safe to call multiple times?

Something like:

    using (IDisposable disposable = GetSomeDisposable())
    {
        //.....
        //......
        return Stg();
    }

I believe it is not a proper place for a return statement, is it?


returning in the middle of a using block

DataSet and DataTable both implement IDisposable, so, by conventional best practices, I should call their Dispose() methods.

However, from what I&#39;ve read so far, DataSet and DataTable don&#39;t actually have any unmanaged resources, so Dispose() doesn&#39;t actually do much.

Plus, I can&#39;t just use `using(DataSet myDataSet...)` because DataSet has a collection of DataTables.

So, to be safe, I&#39;d need to iterate through myDataSet.Tables, dispose of each of the DataTables, then dispose of the DataSet.

So, is it worth the hassle to call Dispose() on all of my DataSets and DataTables?

**Addendum:**

For those of you who think that DataSet should be disposed:
In general, the pattern for disposing is to use `using` or `try..finally`, because you want to guarantee that Dispose() will be called.

However, this gets ugly real fast for a collection.  For example, what do you do if one of the calls to Dispose() thrown an exception?  Do you swallow it (which is &quot;bad&quot;) so that you can continue on to dispose the next element?

Or, do you suggest that I just call myDataSet.Dispose(), and forget about disposing the DataTables in myDataSet.Tables? 

Should I Dispose() DataSet and DataTable?

Is it safe to use the `using` statement on a (potentially) null object?  
Consider the following example:

    class Test {
        IDisposable GetObject(string name) {
            // returns null if not found
        }
        
        void DoSomething() {
            using (IDisposable x = GetObject(&quot;invalid name&quot;)) {
                if (x != null) {
                     // etc...
                }
            }
        }
    }

Is it guaranteed that `Dispose` will be called only if the object is not null, and I will not get a `NullReferenceException`?


Will Dispose() be called in a using statement with a null object?

Classes such as `Stream`, `StreamReader`, `StreamWriter` etc implements `IDisposable` interface. That means, we can call `Dispose()` method on objects of these classes. They&#39;ve also defined a `public` method called `Close()`. Now that confuses me, as to what should I call once I&#39;m done with objects? What if I call both? 

My current code is this:


    using (Stream responseStream = response.GetResponseStream())
    {
       using (StreamReader reader = new StreamReader(responseStream))
       {
          using (StreamWriter writer = new StreamWriter(filename))
          {
             int chunkSize = 1024;
             while (!reader.EndOfStream)
             {
                char[] buffer = new char[chunkSize];
                int count = reader.Read(buffer, 0, chunkSize);
                if (count != 0)
                {
                   writer.Write(buffer, 0, count);
                }
             }
             writer.Close();
          }
          reader.Close();
       }
    }

As you see, I&#39;ve written `using()` constructs, which automatically call `Dispose()` method on each object. But I also call `Close()` methods. Is it right?

Please suggest me the best practices when using stream objects. :-)

MSDN example doesn&#39;t use `using()` constructs, and call `Close()` method:

  - [How to: Download Files with FTP][1]

Is it good?

[1]:http://msdn.microsoft.com/en-us/library/ms229711.aspx

Should I call Close() or Dispose() for stream objects?

The .NET [IDisposable Pattern](http://msdn.microsoft.com/en-us/library/system.idisposable.aspx) *implies* that if you write a finalizer, and implement IDisposable, that your finalizer needs to explicitly call Dispose.
This is logical, and is what I&#39;ve always done in the rare situations where a finalizer is warranted.

However, what happens if I just do this:

    class Foo : IDisposable
    {
         public void Dispose(){ CloseSomeHandle(); }
    }

and don&#39;t implement a finalizer, or anything. Will the framework call the Dispose method for me?

Yes I realise this sounds dumb, and all logic implies that it won&#39;t, but I&#39;ve always had 2 things at the back of my head which have made me unsure.

1. Someone a few years ago once told me that it would in fact do this, and that person had a very solid track record of &quot;knowing their stuff.&quot;

2. The compiler/framework does other &#39;magic&#39; things depending on what interfaces you implement (eg: foreach, extension methods, serialization based on attributes, etc), so it makes sense that this might be &#39;magic&#39; too. 

While I&#39;ve read a lot of stuff about it, and there&#39;s been lots of things implied, I&#39;ve never been able to find a **definitive** Yes or No answer to this question.

Will the Garbage Collector call IDisposable.Dispose for me?

Start with these simple classes...
----------------------------------
Let&#39;s say I have a simple set of classes like this: 

    class Bus
    {
        Driver busDriver = new Driver();
    }

    class Driver
    {
        Shoe[] shoes = { new Shoe(), new Shoe() };
    }

    class Shoe
    {
        Shoelace lace = new Shoelace();
    }

    class Shoelace
    {
        bool tied = false;
    }

A `Bus` has a `Driver`, the `Driver` has two `Shoe`s, each `Shoe` has a `Shoelace`. All very silly.  

Add an IDisposable object to Shoelace
------------------------------------
Later I decide that some operation on the `Shoelace` could be multi-threaded, so I add an `EventWaitHandle` for the threads to communicate with. So `Shoelace` now looks like this:

    class Shoelace
    {
        private AutoResetEvent waitHandle = new AutoResetEvent(false);
        bool tied = false;
        // ... other stuff ..
    }

Implement IDisposable on Shoelace
---------------------------------
But now [Microsoft&#39;s FxCop][1] will complain: *&quot;Implement IDisposable on &#39;Shoelace&#39; because it creates members of the following IDisposable types: &#39;EventWaitHandle&#39;.&quot;*

Okay, I implement `IDisposable` on `Shoelace` and my neat little class becomes this horrible mess:

    class Shoelace : IDisposable
    {
        private AutoResetEvent waitHandle = new AutoResetEvent(false);
        bool tied = false;
        private bool disposed = false;

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        ~Shoelace()
        {
            Dispose(false);
        }

        protected virtual void Dispose(bool disposing)
        {
            if (!this.disposed)
            {
                if (disposing)
                {
                    if (waitHandle != null)
                    {
                        waitHandle.Close();
                        waitHandle = null;
                    }
                }
                // No unmanaged resources to release otherwise they&#39;d go here.
            }
            disposed = true;
        }
    }

Or (as pointed out by commenters) since `Shoelace` itself has no unmanaged resources, I might use the simpler dispose implementation without needing the `Dispose(bool)` and Destructor:

    class Shoelace : IDisposable
    {
        private AutoResetEvent waitHandle = new AutoResetEvent(false);
        bool tied = false;

        public void Dispose()
        {
            if (waitHandle != null)
            {
                waitHandle.Close();
                waitHandle = null;
            }
            GC.SuppressFinalize(this);
        }
    }


Watch in horror as IDisposable spreads
--------------------------------------
Right that&#39;s that fixed. But now FxCop will complain that `Shoe` creates a `Shoelace`, so `Shoe` must be `IDisposable` too. 

And `Driver` creates `Shoe` so `Driver` must be `IDisposable`.
And `Bus` creates `Driver` so `Bus` must be `IDisposable` and so on.

Suddenly my small change to `Shoelace` is causing me a lot of work and my boss is wondering why I need to checkout `Bus` to make a change to `Shoelace`.

The Question
------------
How do you prevent this spread of `IDisposable`, but still ensure that your unmanaged objects are properly disposed?


  [1]: https://en.wikipedia.org/wiki/FxCop

How do you prevent IDisposable from spreading to all your classes?

I&#39;ve noticed that in some case, Visual Studio recommends to do this

    await using var disposable = new Disposable();
    // Do something

Instead of this

    using var disposable = new Disposable();
    // Do something


What is the difference between `using` and `await using`?

How should I decide which one to use?

What is the difference between using and await using? And how can I decide which one to use?

I&#39;ve the following code

    using(MemoryStream ms = new MemoryStream())
    {
         //code
         return 0;
    }

The `dispose()` method is called at the end of `using` statement braces `}` right? Since I  `return` before the end of the `using` statement, will the `MemoryStream` object be disposed properly? What happens here?

What happens if i return before the end of using statement? Will the dispose be called?

Is there a method, or some other light-weight way, to check if a reference is to a disposed object?

P.S. - This is just a curiousity (sleep well, not in production code).  Yes, I know I can catch the `ObjectDisposedException` upon trying to access a member of the object.

How does one tell if an IDisposable object reference is disposed?

I know from reading [the Microsoft documentation](https://docs.microsoft.com/dotnet/api/system.idisposable) that the &quot;primary&quot; use of the `IDisposable` interface is to clean up unmanaged resources.

To me, &quot;unmanaged&quot; means things like database connections, sockets, window handles, etc.  But, I&#39;ve seen code where the `Dispose()` method is implemented to free _managed_ resources, which seems redundant to me, since the garbage collector should take care of that for you.

For example:

    public class MyCollection : IDisposable
    {
        private List&lt;String&gt; _theList = new List&lt;String&gt;();
        private Dictionary&lt;String, Point&gt; _theDict = new Dictionary&lt;String, Point&gt;();

        // Die, clear it up! (free unmanaged resources)
        public void Dispose()
        {
            _theList.clear();
            _theDict.clear();
            _theList = null;
            _theDict = null;
        }

My question is, does this make the garbage collector free memory used by `MyCollection` any faster than it normally would?

**edit**:  So far people have posted some good examples of using IDisposable to clean up unmanaged resources such as database connections and bitmaps.  But suppose that `_theList` in the above code contained a million strings, and you wanted to free that memory _now_, rather than waiting for the garbage collector.  Would the above code accomplish that?

Proper use of the IDisposable interface

ASP.NET Core uses extension methods on `IServiceCollection` to set up dependency injection, then when a type is needed it uses the appropriate method to create a new instance:

* `AddTransient&lt;T&gt;` - adds a type that is created again each time it&#39;s requested.
* `AddScoped&lt;T&gt;` - adds a type that is kept for the scope of the request.
* `AddSingleton&lt;T&gt;` - adds a type when it&#39;s first requested and keeps hold of it.

I have types that implement `IDisposable` and that will cause problems if they aren&#39;t disposed - in each of those patterns when is `Dispose` actually called?

Is there anything I need to add (such as exception handling) to ensure that the instance is always disposed?

When are .NET Core dependency injected instances disposed?

I&#39;m going through a big refactoring / speed tweaking of one of my larger MVC apps.  It has been deployed to production for a few months now, and I was starting to get timeouts waiting for connections in the connection pool.  I have tracked the issue down to the connections not getting disposed properly.

In light of that, I have since made this change to my base controller:

    public class MyBaseController : Controller
    {
        private ConfigurationManager configManager;  // Manages the data context.

        public MyBaseController()
        {
             configManager = new ConfigurationManager();
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (this.configManager != null)
                {
                    this.configManager.Dispose();
                    this.configManager = null;
                }
            }

            base.Dispose(disposing);
        }
    }

Now, I have two questions:

 1. **Am I introducing a race condition?** Since the `configManager` manages the `DataContext` that exposes `IQueryable&lt;&gt;` parameters to
    the views,  I need to make sure that `Dispose()` will not be called
    on the controller before the view finishes rendering.
 2. **Does the MVC framework call `Dispose()` on the Controller before or after the view is rendered?  Or, does the MVC framework leave that
    up to the GarbageCollector?**

ASP MVC: When is IController Dispose() called?

C# 2008

I have been working on this for a while now, and I am still confused about the use of finalize and dispose methods in code. My questions are below:

 1. I know that we only need a finalizer while disposing unmanaged resources. However, if there are managed resources that make calls to unmanaged resources, would it still need to implement a finalizer?

 2. However, if I develop a class that doesn&#39;t use any unmanaged resource -  directly or indirectly, should I implement the `IDisposable` to allow the clients of that class to use the &#39;using statement&#39;? 

    Would it be feasible to implement IDisposable just to enable clients of your class to use the using statement?

        using(myClass objClass = new myClass())
        {
            // Do stuff here
        }

 3. I have developed this simple code below to demonstrate the Finalize/dispose use:


        public class NoGateway : IDisposable
        {
            private WebClient wc = null;
       
            public NoGateway()
            {
                wc = new WebClient();
                wc.DownloadStringCompleted += wc_DownloadStringCompleted;
            }
      
      
            // Start the Async call to find if NoGateway is true or false
            public void NoGatewayStatus()
            {
                // Start the Async&#39;s download
                    // Do other work here
                wc.DownloadStringAsync(new Uri(www.xxxx.xxx));
            }
      
            private void wc_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
            {
                // Do work here
            }
      
            // Dispose of the NoGateway object
            public void Dispose()
            {
                wc.DownloadStringCompleted -= wc_DownloadStringCompleted;
                wc.Dispose();
                GC.SuppressFinalize(this);
            }
        }

Question about the source code:

 1. Here I have not added the finalizer, and normally the finalizer will be called by the GC, and the finalizer will call the Dispose. As I don&#39;t have the finalizer, when do I call the Dispose method? Is it the client of the class that has to call it?

    So my class in the example is called NoGateway and the client could use and dispose of the class like this:  
    

        using(NoGateway objNoGateway = new NoGateway())
        {
            // Do stuff here   
        }

    Would the Dispose method be automatically called when execution reaches the end of the using block, or does the client have to manually call the dispose method? i.e.

        NoGateway objNoGateway = new NoGateway();
        // Do stuff with object
        objNoGateway.Dispose(); // finished with it


 2. I am using the `WebClient` class in my `NoGateway` class. Because `WebClient` implements the `IDisposable` interface, does this mean that `WebClient` indirectly uses unmanaged resources? Is there a hard and fast rule to follow this? How do I know that a class uses unmanaged resources?

Use of Finalize/Dispose method in C#

When should one call `DbContext.dispose()` with entity framework?

1. **Is this imaginary method bad?** 

        public static string GetName(string userId)
        {
            var context = new DomainDbContext();
            var userName = context.UserNameItems.FirstOrDefault(x =&gt; x.UserId == userId);
            context.Dispose();
            return userName;
        }

22. **Is this better?**

        public static string GetName(string userId)
        {
            string userName;
            using(var context = new DomainDbContext()) {
                userName = context.UserNameItems.FirstOrDefault(x =&gt; x.UserId == userId);
                context.Dispose();
            }
            return userName;
        }

3. **Is this even better, that is, should one NOT call context.Dispose() when using using()?**

        public static string GetName(string userId)
        {
            string userName;
            using(var context = new DomainDbContext()) {
                userName = context.UserNameItems.FirstOrDefault(x =&gt; x.UserId == userId);
            }
            return userName;
        }

Entity Framework and calling context.dispose()

[System.Net.Http.HttpClient](http://msdn.microsoft.com/en-us/library/hh193681.aspx) and [System.Net.Http.HttpClientHandler](http://msdn.microsoft.com/en-us/library/system.net.http.httpclienthandler.aspx) in .NET Framework 4.5 implement IDisposable (via [System.Net.Http.HttpMessageInvoker](http://msdn.microsoft.com/en-us/library/system.net.http.httpmessageinvoker.aspx)).

The [`using` statement documentation]((http://msdn.microsoft.com/en-us/library/yh598w02.aspx)) says:

&gt; As a rule, when you use an IDisposable object, you should declare and
&gt; instantiate it in a using statement.

[This answer](https://stackoverflow.com/a/12374486/376366) uses this pattern:

    var baseAddress = new Uri(&quot;http://example.com&quot;);
    var cookieContainer = new CookieContainer();
    using (var handler = new HttpClientHandler() { CookieContainer = cookieContainer })
    using (var client = new HttpClient(handler) { BaseAddress = baseAddress })
    {
        var content = new FormUrlEncodedContent(new[]
        {
            new KeyValuePair&lt;string, string&gt;(&quot;foo&quot;, &quot;bar&quot;),
            new KeyValuePair&lt;string, string&gt;(&quot;baz&quot;, &quot;bazinga&quot;),
        });
        cookieContainer.Add(baseAddress, new Cookie(&quot;CookieName&quot;, &quot;cookie_value&quot;));
        var result = client.PostAsync(&quot;/test&quot;, content).Result;
        result.EnsureSuccessStatusCode();
    }

But the most visible examples from Microsoft don&#39;t call `Dispose()` either explicitly or implicitly. For instance:

* The [original blog article](http://blogs.msdn.com/b/henrikn/archive/2012/02/16/httpclient-is-here.aspx) announcing the relase of HttpClient.
* The actual [MSDN documentation](http://msdn.microsoft.com/en-us/library/system.net.http.httpclient.aspx) for HttpClient.
* [BingTranslateSample](http://aspnet.codeplex.com/SourceControl/changeset/view/9cb7243bd9fe3b2df484bf2409af943f39533588#Samples/HttpClient/BingTranslateSample/Program.cs)
* [GoogleMapsSample](http://aspnet.codeplex.com/SourceControl/changeset/view/9cb7243bd9fe3b2df484bf2409af943f39533588#Samples/HttpClient/GoogleMapsSample/Program.cs)
* [WorldBankSample](http://aspnet.codeplex.com/SourceControl/changeset/view/9cb7243bd9fe3b2df484bf2409af943f39533588#Samples/HttpClient/WorldBankSample/Net45/Program.cs)

In the [announcement](http://blogs.msdn.com/b/henrikn/archive/2012/02/16/httpclient-is-here.aspx)&#39;s comments, someone asked the Microsoft employee:

&gt; After checking your samples, I saw that you didn&#39;t perform the dispose
&gt; action on HttpClient instance. I have used all instances of HttpClient
&gt; with using statement on my app and I thought that it is the right way
&gt; since HttpClient  implements the IDisposable interface. Am I on the
&gt; right path?

His answer was:

&gt; In general that is correct although you have to be careful with
&gt; &quot;using&quot; and async as they dont&#39; really mix in .Net 4, In .Net 4.5 you
&gt; can use &quot;await&quot; inside a &quot;using&quot; statement.
&gt; 
&gt; Btw, you can reuse the same HttpClient as many times are [as] you like so
&gt; typically you won&#39;t create/dispose them all the time.

The second paragraph is superfluous to this question, which is not concerned about how many times you can use an HttpClient instance, but about if it is necessary to dispose it after you no longer need it.

(Update: in fact that second paragraph is the key to the answer, as provided below by @DPeden.)

So my questions are:

1. Is it necessary, given the current implementation (.NET Framework 4.5), to call Dispose() on HttpClient and HttpClientHandler instances? Clarification: by &quot;necessary&quot; I mean if there are any negative consequences for not disposing, such as resource leakage or data corruption risks.

2. If it&#39;s not necessary, would it be a &quot;good practice&quot; anyway, since they implement IDisposable?

3. If it&#39;s necessary (or recommended), is [this code](https://stackoverflow.com/a/12374486/376366) mentioned above implementing it safely (for .NET Framework 4.5)?

4. If these classes don&#39;t require calling Dispose(), why were they implemented as IDisposable?

5. If they require, or if it&#39;s a recommended practice, are the Microsoft examples misleading or unsafe?

Do HttpClient and HttpClientHandler have to be disposed between requests?

I was having a discussion with a colleague recently about the value of `Dispose` and types that implement `IDisposable`.

I think there is value in implementing `IDisposable` for types that should clean up as soon as possible, **even if there are no unmanaged resources to clean up**.

My colleague thinks differently; implementing `IDisposable` if you don&#39;t have any unmanaged resources isn&#39;t necessary as your type will eventually be garbage collected.

My argument was that if you had an ADO.NET connection that you wanted to close as soon as possible, then implementing `IDisposable` and `using new MyThingWithAConnection()` would make sense.  My colleage replied that, under the covers, an ADO.NET connection is an **unmanaged resource**.  My reply to his reply  was that **everything ultimately is an unmanaged resource**.

I am aware of the [recommended disposable pattern][1] where you **free managed and unmanaged resources if `Dispose` is called** but **only free unmanaged resources if called via the finalizer/destructor** (and blogged a while ago about how to [alert consumers of improper use of your IDisposable types][2])

So, my question is, if you&#39;ve got a type that doesn&#39;t contain unmanaged resources, is it worth implementing `IDisposable`?


  [1]: http://msdn.microsoft.com/en-us/library/b1yfkh5e%28v=vs.71%29.aspx
  [2]: http://stevedunns.blogspot.co.uk/2009/03/idisposable-alerts.html

Should &quot;Dispose&quot; only be used for types containing unmanaged resources?

**Note** This is *not* a question about how to implement or emulate duck typing in C#...

For several years I was under the impression that certain C# language features were depdendent on data structures defined in the language itself (which always seemed like an odd chicken &amp; egg scenario to me). For example, I was under the impression that the `foreach` loop was only available to use with types that implemented `IEnumerable`.

Since then I&#39;ve come to understand that the C# compiler uses duck typing to determine whether an object can be used in a foreach loop, looking for a `GetEnumerator` method rather than `IEnumerable`. This makes a lot of sense as it removes the chicken &amp; egg conundrum.

I&#39;m a little confused as to why this isn&#39;t doesn&#39;t seem to be the case with the `using` block and `IDisposable`. Is there any particular reason the compiler can&#39;t use duck typing &amp; look for a `Dispose` method? What&#39;s the reason for this inconsistency?

Perhaps there&#39;s something else going on under the hood with IDisposable?

*Discussing why you would **ever** have an object with a Dispose method that didn&#39;t implement IDisposable is outside the scope of this question :)*

Duck typing in the C# compiler

In .NET, under which circumstances should I use `GC.SuppressFinalize()`?

What advantage(s) does using this method give me?

When should I use GC.SuppressFinalize()?

In C#, Does foreach automatically call Dispose on any object implementing IDisposable?


http://msdn.microsoft.com/en-us/library/aa664754(v=vs.71).aspx seems to indicate that it does:

*Otherwise, the collection expression is of a type that implements System.IEnumerable, and the expansion of the foreach statement is:
Copy

    IEnumerator enumerator = 
            ((System.Collections.IEnumerable)(collection)).GetEnumerator();
    try {
       while (enumerator.MoveNext()) {
          ElementType element = (ElementType)enumerator.Current;
          statement;
       }
    }
    finally {
       IDisposable disposable = enumerator as System.IDisposable;
       if (disposable != null) disposable.Dispose();
    }

Does foreach automatically call Dispose?

&gt; **Possible Duplicate:**  
&gt; [Will the Garbage Collector call IDisposable.Dispose for me?](https://stackoverflow.com/questions/45036/will-the-garbage-collector-call-idisposable-dispose-for-me)  

&lt;!-- End of automatically inserted text --&gt;

I have a Class which has some unmanaged resources. My class implements the `IDisposable` interface and releases the unmanaged resources in the `Dispose()` method. Do I have to call the `Dispose()` method or will it be automatically called somehow? Will the Garbage Collector call it?

Is IDisposable.Dispose() called automatically?

So, I&#39;ve registered a named client with the services collection in my Startup.cs:

&lt;!-- language-all: lang-cs --&gt;

    services.AddHttpClient(someServiceName, 
                           client =&gt; client.BaseAddress = baseAddress);

and now can inject an `IHttpClientFactory` from my service provider.

Using this `IHttpClientFactory`, I conjure up a client instance:

    var client = httpClientFactory.CreateClient(someServiceName)

Once upon a time, it was necessary to be very careful about the disposing of `HttpClient` instances, as it was [rarely the right thing to do][1]. 

However, now we have `HttpClientFactory`, does this matter any more? Should/Can this `client` be disposed without worry? e.g.

    using (var httpClient = httpClientFactory.CreateClient(someServiceName))
    using (var response = await httpClient.PostAsync(somePath, someData))
    {
        var content = await response.Content.ReadAsAsync&lt;SomeResponse&gt;();
        //...
    }


  [1]: https://aspnetmonsters.com/2016/08/2016-08-27-httpclientwrong/

Should HttpClient instances created by HttpClientFactory be disposed?

Is there any guidance or best practices around who should call `Dispose()` on disposable objects when they have been passed into another object&#39;s methods or constuctor?

Here&#39;s a couple of examples as to what I mean.

IDisposable object is passed into a method (Should it dispose of it once its done?):

    public void DoStuff(IDisposable disposableObj)
    {
        // Do something with disposableObj
        CalculateSomething(disposableObj)

        disposableObj.Dispose();
    }

IDisposable object is passed into a method and a reference is kept (Should it dispose of it when `MyClass` is disposed?):

    public class MyClass : IDisposable
    {
        private IDisposable _disposableObj = null;
    
        public void DoStuff(IDisposable disposableObj)
        {
            _disposableObj = disposableObj;
        }
    
        public void Dispose()
        {
            _disposableObj.Dispose();
        }
    }

I&#39;m currently thinking that in the first example the *caller* of `DoStuff()` should dispose of the object as it probably created the object. But in the second example it feels like `MyClass` should dispose of the object as it keeps a reference to it. The problem with this is that the calling class might not know `MyClass` has kept a reference and therefore might decide to dispose of the object before `MyClass` has finished using it.
Are there any standard rules for this sort of scenario? If there are, do they differ when the disposable object is being passed into a constructor?

Who should call Dispose on IDisposable objects when passed into another object?

In C#, if a class, such as a manager class, does not have resources, is there any benefit to having it ` : IDisposable `?

Simple example:

    public interface IBoxManager
    {
     int addBox(Box b);
    }

    public class BoxManager : IBoxManager
    {
     public int addBox(Box b)
     {
      using(dataContext db = new dataContext()){
       db.Boxes.add(b);
       db.SaveChanges();
      }
      return b.id;
     }
    }

Will there be any benefit in memory use when using BoxManager if it also implements IDisposable? `public class BoxManager : IBoxManager , IDisposable`

For example:

    BoxManager bm = new BoxManager();
    bm.add(myBox);
    bm.dispose();//is there benefit to doing this?

Is there any benefit to implementing IDisposable on classes which do not have resources?

Starting from the following situation:

    public interface ISample
    {
    }
    
    public class SampleA : ISample
    {
       // has some (unmanaged) resources that needs to be disposed
    }
    
    public class SampleB : ISample
    {
       // has no resources that needs to be disposed
    }

The class SampleA should implement the interface IDisposable for releasing resources.
You could solve this in two ways:

**1. Add the required interface to the class SampleA:**

    public class SampleA : ISample, IDisposable
    {
       // has some (unmanaged) resources that needs to be disposed
    }

**2. Add it to the interface ISample and force derived classes to implement it:**

    public interface ISample : IDisposable
    {
    }

If you put it into the interface, you force any implementation to implement IDisposable even if they have nothing to dispose. On the other hand, it is very clear to see that the concrete implementation of an interface requires a dispose/using block and you don&#39;t need to cast as IDisposable for cleaning up. There might be some more pros/cons in both ways... why would you suggest to use one way preferred to the other?



Declare IDisposable for the class or interface?

It has been my understanding that the [`using` statement][1] in .NET calls an `IDisposable` object&#39;s `Dispose()` method once the code exits the block.

Does the `using` statement do anything else? If not, it would seem that the following two code samples achieve the exact same thing:

	Using Con as New Connection()
		Con.Open()
		&#39;do whatever &#39;
	End Using

	Dim Con as New Connection()
	Con.Open()
	&#39;do whatever &#39;
	Con.Dispose()

I will give the best answer to whoever confirms that I am correct or points out that I am wrong and explains why. Keep in mind that I am aware that certain classes *can do different things* in their `Dispose()` methods. This question is about whether or not the `using` statement achieves the exact same result as calling an object&#39;s `Dispose()` method.

  [1]: https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/using-statement

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