There is no such access modifier: the closest modifier is `internal`, but the unit of protection is the assembly in which the class resides, not its namespace.

One could argue that it is possible to achieve similar level of control using `internal`, because both kinds of restriction keep outsiders from accessing the implementation details of your library. The only person to whom it makes a difference is you, the writer of the library, and you are in full control of what to expose and what to hide anyway. Essentially, it means that if you do not want to use a class outside its namespace, simply refrain from using it; if the class is `internal`, nobody else will be able to use that class either.

In .NET there are assemlies(dll or exe files), you can use `internal` modifier to limit access only within the same assembly

&gt; Is there a specific reason for this?

Mostly, it&#39;s because there are some key [differences between packages and namespaces][1]

To simplify what&#39;s already been said in the linked question and here: Namespaces in C# are mostly to help with organizing an assembly&#39;s contents, both internally and externally.  Java packages have more in common with C# assemblies, and there is an access modifier in C# that restricts to the assembly level: [internal][2]. 


  [1]: https://stackoverflow.com/q/9249357/2630934
  [2]: http://msdn.microsoft.com/en-us/library/7c5ka91b%28v=vs.110%29.aspx

I have multiple threads running which access singleton object and call its method and pass objects in it. In the method I do some calculations only on recieved object.
I have heard that there would not be any problem in this case cause it is stateless and it is free for all.

My question is how it is free for all?
I want to know how multiple threads can call the shared method in their own thread without overwriting the passed objects of other threads? 
Please explain in terms of memory allocation wise and at stack level.


    class Singleton class{
    
    	//no shared class or object variables and only one copy of this Singleton object exists.
    
    	Object someMethod(Object o){
    		//do some calculation or logic on the object o and return some string result
    	}
    
    }

how multiple threads invoke singleton object&#39;s method and work on them?

This website implies that clearing a vector MAY change the capacity:

http://en.cppreference.com/w/cpp/container/vector/clear

&gt; Many implementations will not release allocated memory after a call
&gt; to clear(), effectively leaving the capacity() of the vector
&gt; unchanged.

But according to @JamesKanze this is wrong and the standard mandates that clear will not change capacity.

What does the standard say?

What does the standard say about how calling clear on a vector changes the capacity?

In java you have package level protection that ensures classes are only usable within the package. 

Namespaces in C# act more or less like packages. But C# does not have a protection level for protecting classes within a namespace.

Is there a specific reason for this?

C# access modifier for exposing class only within namespace

In java you have package level protection that ensures classes are only usable within the package.
Namespaces in C# act more or less like packages. But C# does not have a protection level for protecting classes within a namespace.
Is there a specific reason for this?

I have this legacy code :
  
     private void conecta()
     {  
         if (conexao.State == ConnectionState.Closed)
             conexao.Open();
     }

     public List&lt;string[]&gt; get_dados_historico_verificacao_email_WEB(string email)
     {
         List&lt;string[]&gt; historicos = new List&lt;string[]&gt;();
         conecta();
        
         sql = 
             @&quot;SELECT * 
             FROM historico_verificacao_email 
             WHERE nm_email = &#39;&quot; + email + @&quot;&#39; 
             ORDER BY dt_verificacao_email DESC, hr_verificacao_email DESC&quot;;
 
         com = new SqlCommand(sql, conexao);
         SqlDataReader dr = com.ExecuteReader();
         
         if (dr.HasRows)
         {
             while (dr.Read())
             {
                 string[] dados_historico = new string[6];
                 dados_historico[0] = dr[&quot;nm_email&quot;].ToString();
                 dados_historico[1] = dr[&quot;dt_verificacao_email&quot;].ToString();
                 dados_historico[1] = dados_historico[1].Substring(0, 10);
                 dados_historico[2] = dr[&quot;hr_verificacao_email&quot;].ToString();
                 dados_historico[3] = dr[&quot;ds_tipo_verificacao&quot;].ToString();

                 sql = 
                     @&quot;SELECT COUNT(e.cd_historico_verificacao_email) QT 
                     FROM emails_lidos e 
                     WHERE e.cd_historico_verificacao_email = 
                         &#39;&quot; + dr[&quot;cd_historico_verificacao_email&quot;].ToString() + &quot;&#39;&quot;;
                 
                 tipo_sql = &quot;sele&#231;&#227;o&quot;;
                 conecta();
                 com2 = new SqlCommand(sql, conexao);

                 SqlDataReader dr3 = com2.ExecuteReader();
                 while (dr3.Read())
                 {
                     //quantidade de emails lidos naquela verifica&#231;&#227;o
                     dados_historico[4] = dr3[&quot;QT&quot;].ToString(); 
                 }
                 dr3.Close();
                 conexao.Close();
                 
                 //login
                 dados_historico[5] = dr[&quot;cd_login_usuario&quot;].ToString();
                 historicos.Add(dados_historico);
             }
             dr.Close();
         }
         else
         { 
             dr.Close();
         }
         
         conexao.Close();
         return historicos;
     }

&lt;br/&gt;
I have created two separates commands to correct the issue, but it still continues: &quot;There is already an open DataReader associated with this Command which must be closed first&quot;.

An additional info: the same code is working in another app.

Error &quot;There is already an open DataReader associated with this Command which must be closed first&quot; when using 2 distinct commands

I am writing a program which needs the namespace of the program but I cant seem to figure out how to retrieve it. I would like the end result to be in a string.

I was able to find an MSDN page about this topic but it proved to be unhelpful to myself.
http://msdn.microsoft.com/en-us/library/system.type.namespace.aspx

Any help would be appreciated. The program is written in C#.


EDIT: Sorry guys, this is not a console application.

How can I retrieve the namespace to a string C#

If I have this method:

    public void doSomething (Dictionary&lt;String, Object&gt; data)
    {
        JObject jsonObject = new JObject(data);
        ...
    }

I get a `System.ArgumentException` on the line where I create the JObject. I&#39;m using Newton-King&#39;s Json.net wrapper.

The error I get is:

&gt; A first chance exception of type &#39;System.ArgumentException&#39; occurred
&gt; in Newtonsoft.Json.DLL An exception of type &#39;System.ArgumentException&#39;
&gt; occurred in Newtonsoft.Json.DLL but was not handled in user code

What am I doing wrong here?

Argument Exception when creating JObject

The [async-await][1] pattern of .net 4.5 is paradigm changing. It&#39;s almost too good to be true.

I&#39;ve been porting some IO-heavy code to async-await because blocking is a thing of the past. 

Quite a few people are comparing async-await to a zombie infestation and I found it to be rather accurate. Async code likes other async code (you need an async function in order to await on an async function). So more and more functions become async and this keeps growing in your codebase. 

Changing functions to async is somewhat repetitive and unimaginative work. Throw an `async` keyword in the declaration, wrap the return value by `Task&lt;&gt;` and you&#39;re pretty much done. It&#39;s rather unsettling how easy the whole process is, and pretty soon a text-replacing script will automate most of the &quot;porting&quot; for me.

And now the question.. If all my code is slowly turning async, why not just make it all async by default?

The obvious reason I assume is performance. Async-await has a its overhead and code that doesn&#39;t need to be async, preferably shouldn&#39;t. But if performance is the sole problem, surely some clever optimizations can remove the overhead automatically when it&#39;s not needed. I&#39;ve read about the [&quot;fast path&quot;][2] optimization, and it seems to me that it alone should take care of most of it.

Maybe this is comparable to the paradigm shift brought on by garbage collectors. In the early GC days, freeing your own memory was definitely more efficient. But the masses still chose automatic collection in favor of safer, simpler code that might be less efficient (and even that arguably isn&#39;t true anymore). Maybe this should be the case here? Why shouldn&#39;t all functions be async?


  [1]: http://msdn.microsoft.com/en-us/library/vstudio/hh191443.aspx
  [2]: http://blogs.msdn.com/b/lucian/archive/2011/04/15/async-ctp-refresh-design-changes.aspx

Why shouldn&#39;t all functions be async by default?

The general answers such as [here][1] and [here][2]  to *fire-and-forget* questions is not to use async/await, but to use `Task.Run` or `TaskFactory.StartNew` passing in the synchronous method instead.&lt;br/&gt; However, sometimes the method that I want to *fire-and-forget* is async and there is no equivalent sync method. 

**Update Note/Warning:** As Stephen Cleary pointed out below, it is dangerous to continue working on a request after you have sent the response. The reason is because the AppDomain may be shut down while that work is still in progress. See the link in his response for more information. Anyways, I just wanted to point that out upfront, so that I don&#39;t send anyone down the wrong path.

I think my case is valid because the actual work is done by a different system (different computer on a different server) so I only need to know that the message has left for that system. If there is an exception there is nothing that the server or user can do about it and it does not affect the user, all I need to do is refer to the exception log and clean up manually (or implement some automated mechanism). If the AppDomain is shut down I will have a residual file in a remote system, but I will pick that up as part of my usual maintenance cycle and since its existence is no longer known by my web server (database) and its name is uniquely timestamped, it will not cause any issues while it still lingers. 

It would be ideal if I had access to a persistence mechanism as Stephen Cleary pointed out, but unfortunately I don&#39;t at this time. 

I considered just pretending that the DeleteFoo request has completed fine on the client side (javascript) while keeping the request open, but I need information in the response to continue, so it would hold things up. 

So, the original question...  

for example: 

    //External library
    public async Task DeleteFooAsync();

In my asp.net mvc code I want to call DeleteFooAsync in a fire-and-forget fashion - I don&#39;t want to hold up the response waiting for DeleteFooAsync to complete. If DeleteFooAsync fails (or throws an exception) for some reason, there is nothing that the user or the program can do about it so I just want to log an error. 

Now, I know that any exceptions will result in unobserved exceptions, so the simplest case I can think of is:

    //In my code
    Task deleteTask = DeleteFooAsync()

    //In my App_Start
    TaskScheduler.UnobservedTaskException += ( sender, e ) =&gt;
    {
        m_log.Debug( &quot;Unobserved exception! This exception would have been unobserved: {0}&quot;, e.Exception );
        e.SetObserved();
    };

Are there any risks in doing this? 

The other option that I can think of is to make my own wrapper such as: 

    private void async DeleteFooWrapperAsync()
    {
        try
        {
            await DeleteFooAsync();
        }
        catch(Exception exception )
        {
            m_log.Error(&quot;DeleteFooAsync failed: &quot; + exception.ToString());
        }
    }

and then call that with TaskFactory.StartNew (probably wrapping in an async action). However this seems like a lot of wrapper code each time I want to call an async method in a fire-and-forget fashion. 

My question is, what it the correct way to call an async method in a fire-and-forget fashion?

**UPDATE:**

Well, I found that the following in my controller (not that the controller action needs to be async because there are other async calls that are awaited):

    [AcceptVerbs( HttpVerbs.Post )]
    public async Task&lt;JsonResult&gt; DeleteItemAsync()
    {
        Task deleteTask = DeleteFooAsync();
        ...
    }

caused an exception of the form:

&gt; Unhandled Exception: System.NullReferenceException: Object reference
&gt; not set to an instance of an object. at System.Web.ThreadContext.AssociateWithCurrentThread(BooleansetImpersonationContext)

This is discussed [here][3] and seems to be to do with the SynchronizationContext and &#39;the returned Task was transitioned to a terminal state before all async work completed&#39;.

So, the only method that worked was: 

    Task foo = Task.Run( () =&gt; DeleteFooAsync() );

My understanding of why this works is because StartNew gets a new thread for DeleteFooAsync to work on.

Sadly, Scott&#39;s suggestion below does not work for handling exceptions in this case, because foo is not a DeleteFooAsync task anymore, but rather the task from Task.Run, so does not handle the exceptions from DeleteFooAsync. My UnobservedTaskException does eventually get called, so at least that still works. 

So, I guess the question still stands, how do you do fire-and-forget an async method in asp.net mvc?


  [1]: https://stackoverflow.com/a/12803259/746754
  [2]: https://stackoverflow.com/a/13800486/746754
  [3]: https://connect.microsoft.com/VisualStudio/feedback/details/745956/getting-null-reference-exception-in-asp-net-mvc-4-rc

Fire and forget async method in asp.net mvc

I&#39;ve been using the [JWT](https://www.nuget.org/packages/JWT) library to decode a Json Web Token, and would like to switch to Microsoft&#39;s official JWT implementation, [System.IdentityModel.Tokens.Jwt](https://www.nuget.org/packages/System.IdentityModel.Tokens.Jwt).

The documentation is very sparse, so I&#39;m having a hard time figuring how to accomplish what I&#39;ve been doing with the JWT library.  With the JWT library, there is a Decode method that takes the base64 encoded JWT and turns it into JSON which can then be deserialized. I&#39;d like to do something similar using System.IdentityModel.Tokens.Jwt, but after a fair amount of digging, cannot figure out how.  

For what it&#39;s worth, I&#39;m reading the JWT token from a cookie, for use with Google&#39;s identity framework.

Any help would be appreciated.

Decoding and verifying JWT token using System.IdentityModel.Tokens.Jwt

I have made a NuGet package that works well when I use it from a C# project. It contains a DLL in the `lib/net40` directory, and the DLL gets added as a reference.

Now that NuGet supports C++, how do I actually modify my package so that the DLL can be added as a managed reference in a C++/CLI project? I can&#39;t find any tutorials explaining this. If I try to just add the package as is, I get the following error:

&gt; You are trying to install this package into a project that targets &#39;Native,Version=v0.0&#39;, but the package does not contain any assembly references or content files that are compatible with that framework.

One would think that the solution is to put the files under lib/native, but according to http://docs.nuget.org/docs/reference/support-for-native-projects, that is not supported. Also, simply putting the DLL directly under lib doesn&#39;t seem to do anything.

Apparently, I am supposed to do this with a `.props` or `.targets` file under build/native, but what do I need to put into those files to make this work ?

How can I make my managed NuGet package support C++/CLI projects?

So WPF windows only have four resize mode options: `NoResize`, `CanMinimize`, `CanResize` and `CanResizeWithGrip`. Unfortunately, the options that enable resizing also enable maximizing the window, and those that don&#39;t are useless to me.

Is there an option to disable the maximize button while keeping the resize feature? 

I&#39;d prefer solutions that don&#39;t involve `WinAPI` stuff.

Disable maximize button of WPF window, keeping resizing feature intact

I&#39;m organizing a library project and I have a central manager class named `Scenegraph` and a whole bunch of other classes that live in the Scenegraph namespace.

What I&#39;d really like is for the scenegraph to be `MyLib.Scenegraph` and the other classes to be `MyLib.Scenegraph.*`, but it seems the only way to do that would be to make all the other classes inner classes of `Scenegraph` in the Scenegraph.cs file and that&#39;s just too unwieldy.

Instead, I&#39;ve organized it as `Mylib.Scenegraph.Scenegraph` and `MyLib.Scenegraph.*`, which sort of works but I find Visual Studio gets confused under some conditions as to whether I am referring to the class or the namespace.

Is there a good way to organize this package so it&#39;s convenient for users without glomming all my code together in an unmaintainable mess?

Namespace and class with the same name?

What is the use of `using namespace std`? 

I&#39;d like to see explanation in Layman terms.

What is the use of &quot;using namespace std&quot;?

Would it be possible to have something like this?

    app/models/
    app/models/users/user.rb
    app/models/users/education.rb

The goal is to organize the */app/models* folder better, but without having to namespace the models.

An unanswered question for Rails 3 is here:
https://stackoverflow.com/questions/14236742/rails-3-2-9-and-models-in-subfolders.

Specifying table_name with namespaces seems to work (see https://stackoverflow.com/questions/17975296/rails-4-model-subfolder), but **I want to do this without a namespace**.

Rails 4: organize rails models in sub path without namespacing models?

I am trying to use forward declarations in header files to reduce the number of `#include` used and hence reduce dependencies when users include my header file.

However, I am unable to forward declare where namespaces are used.  See example below.

File `a.hpp`:

    #ifndef __A_HPP__
    #define __A_HPP__
    
    namespace ns1 {
    
       class a {
       public:
          a(const char* const msg);
    
          void talk() const;
    
       private:
          const char* const msg_;
       };
    }
    
    #endif //__A_HPP__

File `a.cpp`:

    #include &lt;iostream&gt;

    #include &quot;a.hpp&quot;

    using namespace ns1;

    a::a(const char* const msg) : msg_(msg) {}

    void a::talk() const { 
       std::cout &lt;&lt; msg_ &lt;&lt; std::endl; 
    }


    
File `consumer.hpp`:

    #ifndef __CONSUMER_HPP__
    #define __CONSUMER_HPP__
    
    // How can I forward declare a class which uses a namespace
    //doing this below results in error C2653: &#39;ns1&#39; : is not a class or namespace name
    // Works with no namespace or if I use using namespace ns1 in header file
    // but I am trying to reduce any dependencies in this header file
    class ns1::a;
    
    class consumer
    {
    public:
       consumer(const char* const text) : a_(text) {}
       void chat() const;
    
    private:
       a&amp; a_;
    };
    
    #endif // __CONSUMER_HPP__
    
Implementation file `consumer.cpp`:

    #include &quot;consumer.hpp&quot;
    #include &quot;a.hpp&quot;
    
    consumer::consumer(const char* const text) : a_(text) {}
    
    void consumer::chat() const {
       a_.talk();
    }
    
Test file `main.cpp`:

    #include &quot;consumer.hpp&quot;
    
    int main() {
       consumer c(&quot;My message&quot;);
       c.chat();
       return 0;
    }

---
**UPDATE**:

Here is my very contrived working code using the answer below.

File `a.hpp`:

    #ifndef A_HPP__
    #define A_HPP__
    
    #include &lt;string&gt;
    
    namespace ns1 {
    
       class a {
       public:
          void set_message(const std::string&amp; msg);
          void talk() const;
    
       private:
          std::string msg_;
       };
    
    } //namespace
    
    #endif //A_HPP__
    
File `a.cpp`:

    #include &lt;iostream&gt;
    #include &quot;a.hpp&quot;
    
    void ns1::a::set_message(const std::string&amp; msg) {
        msg_ = msg;
    }
    void ns1::a::talk() const { 
       std::cout &lt;&lt; msg_ &lt;&lt; std::endl; 
    }
    
File `consumer.hpp`:

    #ifndef CONSUMER_HPP__
    #define CONSUMER_HPP__
    
    namespace ns1
    {
       class a;
    }
    
    class consumer
    {
    public:
       consumer(const char* text);
       ~consumer();
       void chat() const;
    
    private:
       ns1::a* a_;
    };
    
    #endif // CONSUMER_HPP__
    
File `consumer.cpp`:

    #include &quot;a.hpp&quot;
    #include &quot;consumer.hpp&quot;
    
    consumer::consumer(const char* text) {
       a_ = new ns1::a;
       a_-&gt;set_message(text);
    }
    consumer::~consumer() {
       delete a_;
    }
    void consumer::chat() const {
       a_-&gt;talk();
    }
    
    
File `main.cpp`:

    #include &quot;consumer.hpp&quot;
    
    int main() {
       consumer c(&quot;My message&quot;);
       c.chat();
       return 0;
    }


Content Type	Original Author	Original Content on Stackoverflow
Question	Jaco	View Question on Stackoverflow
Solution 1 - C#	Sergey Kalinichenko	View Answer on Stackoverflow
Solution 2 - C#	Alexandr Mihalciuc	View Answer on Stackoverflow
Solution 3 - C#	User	View Answer on Stackoverflow

C# access modifier for exposing class only within namespace

C# Problem Overview

C# Solutions

Solution 1 - C#

Solution 2 - C#

Solution 3 - C#

What does the standard say about how calling clear on a vector changes the capacity?

how multiple threads invoke singleton object's method and work on them?

Attributions