Passing a callback function to another class

Question

I m basically trying to pass a method to another class to be called later  but can t quite figure this out in C   I m still too used to Objective-C    public class Class1       private void btn click object sender  EventArgs e                ServerRequest sr   new ServerRequest            sr DoRequest  myrequest   myCallback              public void myCallback string str                  Then later on I want my ServerRequest class to basically fire the callback function  is this not possible   I m basically phoning home to a server for a login response to my software   I haven t been able to find a way to do this with delegates  continuously get errors   Here is the other class   public class ServerRequest       public void DoRequest string request  Delegate callback                   do stuff             callback  asdf              Is this possible in     In Objective-C this would be simple and I would just do something like    myObject performSelector  selector MyFunctionName   withObjects nil

User · Answer

You have to first declare delegate s type because delegates are strongly typed   public void MyCallbackDelegate  string str     public void DoRequest string request  MyCallbackDelegate callback            do stuff          callback  asdf

User · Answer

What you need is a delegate and a callback  Here is a nice MSDN article that will show you how to use this technique in C

User · Answer

public class Class1                private void btn click object sender  EventArgs e                        ServerRequest sr   new ServerRequest                sr Callback    new ServerRequest CallbackEventHandler sr Callback               sr DoRequest  myrequest                       void sr Callback string something                                    public class ServerRequest               public delegate void CallbackEventHandler string something           public event CallbackEventHandler Callback              public void DoRequest string request                           do stuff                 if  Callback    null                  Callback  bla

User · Answer

You could change your code in this way   public delegate void CallbackHandler string str    public class ServerRequest       public void DoRequest string request  CallbackHandler callback                   do stuff             callback  asdf

User · Answer

You can pass it as Action lt string gt  - which means it is a method with a single parameter of type string that doesn t return anything  void     public void DoRequest string request  Action lt string gt  callback           do stuff         callback  asdf

User · Answer

You could use only delegate which is best for callback functions   public class ServerRequest       public delegate void CallBackFunction string input        public void DoRequest string request  CallBackFunction callback                   do stuff             callback request             and consume this like below   public class Class1               private void btn click object sender  EventArgs e                        ServerRequest sr   new ServerRequest                var callback   new ServerRequest CallBackFunction CallbackFunc               sr DoRequest  myrequest  callback                      void CallbackFunc string something

User · Answer

Delegate is just the base class so you can t use it like that  You could do something like this though   public void DoRequest string request  Action lt string gt  callback            do stuff          callback  asdf

[c#] Passing a callback function to another class

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