The type or namespace 'Semaphore Slim could not be found

Having similar issue to this

http://stackoverflow.com/questions/15658318/using-semaphore-in-c-sharp

I have determined that I have .NET 4.6.4 Preview or greater on my machine.

This is a Unity C# project! If I open the source project in VS I don't see the error and project properties shows I am targeting .Net framework 4. So I guess my question is more to do with the way Unity handles .net classes. Confused whether I should be trying to fix this WITHIN VS in the Solution explorer or...?

My understanding is that System.Threading contains the SempahoreSlim class.

I am using source code from this example
https://www.codeproject.com/articles/488668/csharp-tcp-server

Just a partial code listing (first 50 lines of TcpServer)

Code (csharp):

1.  
2.   using System;
3.   using System.Collections.Generic;
4.   using System.ComponentModel;
5.   using System.Net;
6.   using System.Net.Sockets;
7.   using System.Text;
8.   using System.Threading;
9.    
10.   namespace tcpServer
11.   {
12.   public delegate void tcpServerConnectionChanged(TcpServerConnection connection);
13.   public delegate void tcpServerError(TcpServer server, Exception e);
14.    
15.   public partial class TcpServer : Component
16.   {
17.   private List<TcpServerConnection> connections;
18.   private TcpListener listener;
19.    
20.   private Thread listenThread;
21.   private Thread sendThread;
22.    
23.   private bool m_isOpen;
24.    
25.   private int m_port;
26.   private int m_maxSendAttempts;
27.   private int m_idleTime;
28.   private int m_maxCallbackThreads;
29.   private int m_verifyConnectionInterval;
30.   private Encoding m_encoding;
31.    
32.   private SemaphoreSlim sem;
33.  
34.  
35.   private bool waiting;
36.  

 

Does Unity's scaled down Mono C# implementation have SemaphoreSlim? I'd look into that.

 

Unity uses .net 2.0 still, so it's very possible what you are trying to access is not included. Some day in the future they will support higher versions, I believe they are still in testing/development.

 

But surely there must be a way to incorporate more recent .net classes in Unity projects?

 

You can google the source to most C# classes. As long as it doesn't rely on any new language features, you can drop it straight into your project.

 

Also be very, very sure that the class doesn't depend on a newer version of some part of the .net library. It is possible that the class may see the required libraries/classes there, but the SemaphoreSlim class only works properly with updated versions of those libraries. Since you're working with semaphores, chances are a lot of tweaks and bug fixes may have been made over the years to make sure they work properly.