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How to pass a callback method to another class in C#

I'm using C# and I have an App A and a DLL B I've created.
I'd like to be able to do the following:
In App A, create my callback method:
public void MyAppMethod(string inComing){
Debug.WriteLine("callback returned: " + inComing);
}
In App A, set the CallBack method in B, like B.SetCallback(MyAppMethod);
In DLL B, use the callback to return a string:
private void SomeMethod(){
//do some stuff
MyAppMethod("hello");
}
How can I set this up?

Using Events:
App A:
public void MyAppMethod(string inComing){
Debug.WriteLine("callback returned: " + inComing);
}
B.MyAppMethod += MyAppMethod;
App B:
public event Action<string> MyAppMethod;
private void SomeMethod(){
//do some stuff
if(MyAppMethod!=null) MyAppMethod("hello");
}
Using delegates:
App A:
public void MyAppMethod(string inComing){
Debug.WriteLine("callback returned: " + inComing);
}
B.MyAppMethod = MyAppMethod;
App B:
public Action<string> MyAppMethod;
private void SomeMethod(){
//do some stuff
if(MyAppMethod!=null) MyAppMethod("hello");
}
These codes will work as are. However, there are many important things you must consider before using this code, which you will find on the web

This is the code I ended up using.
APP A:
public void MyCallBack(string status)
{
// Add callback text to the status window
StatTxt.AppendText(status);
}
// Set the callback method in DLL B
B.HollaBack = MyCallBack;
DLL B:
public delegate void CallBackDelegate(string status);
public CallBackDelegate HollaBack
{
get; set;
}
private void DoCallBack(string inMsg)
{
// Make sure the callback method was set
if (HollaBack != null)
{
// send text to the callback method
HollaBack(inMsg);
}
}
// Invoke the callback anywhere within DLL B
DoCallBack("show this in the status window");

Best way to add items to a log window from a Class

I'm trying to add a "log" message from my class to a ListBox on my form. Within the form I would just be able to use lblog.add("message"), but as I'm trying to clean up my code, what is the best way to pass the "message" to the front end?
I found a suggestion that has the code below, but wondering if there is a simpler way?
Form:
// This is all required so that we can call the function from another class
public void publicLogMessage(string message)
{
if (InvokeRequired)
{
Invoke(new OutputDelegate(logMessage), message);
}
}
public delegate void OutputDelegate(string message);
public void logMessage(string message)
{
lblog.Items.Add(DateTime.Now + " " + message);
}
Class:
//This is required so that we can call the "PublicLogMessage" function on the main form
public frmMain formToOutput;
public speechRecognition(frmMain f)
{
formToOutput = f;
}
Usage:
formToOutput.logMessage

You now have a pretty tight coupling between your algorithm and your ouput method. Your algorithm knows all about your output method (for example that it's a form with a specific signature).
I would suggest decoupling it:
private readonly Action<string> log;
public speechRecognition(Action<string> log)
{
this.log = log;
}
public void DoWork()
{
this.log("work started");
// ...
this.log("work in progress");
// ...
this.log("work ended");
}
This class knows nothing about the logging method. It only knows it gets a string. The class controlling both the output method (form) and algorithm (class above) can then link them together:
var form = new YourFormWithLoggingWindow();
var algorithm = new speechRecognition(form.publicLogMessage);
Now the algorithm will log to the form. You could have called it using
var algorithm = new speechRecognition(Console.WriteLine);
and it would log to the console in a Console Application. The algorithm does not care and does not need your form to compile. It's independent. Your form does not know the algorithm either. It's independent, too.
You could even have unit testing that checks the logging:
var log = new List<string>();
var algorithm = new speechRecognition(log.Add);
algorithm.DoWork();
Assert.AreEqual(log.Count, 3);

Use if/else when using InvokeRequired, I don't think there are other optimizations at the moment.
public void publicLogMessage(string message)
{
if (InvokeRequired)
Invoke(new OutputDelegate(logMessage), message);
else
logMessage(message);
}
public delegate void OutputDelegate(string message);
private void logMessage(string message)
{
lblog.Items.Add(DateTime.Now + " " + message);
}

private void listboxlrm(byte[] text)
{
if (this.listBox2.InvokeRequired)
{
SetTextCallback d = new SetTextCallback(listboxlrm);
this.Invoke(d, new object[] { text });
}
else
{
byte[] convert = new byte[text[4]];
Array.Copy(text, 6, convert, 0, text[4]);
string yourtext = System.Text.Encoding.UTF8.GetString(convert);
this.listBox2.Items.Insert(0, string.Format(yourtext));
}
}
I am using that method.... If you use insert always add the top.

ListView not adding a valid string

I'm making a console terminal using ListView for my custom server.
It writes any string that was given to it from the same class Main but refuses if its from another Misc.
Heres a gif of the following code in action
The first part of the gif is from myFunction(). As you can see, the messagebox shows that str in stringToConsole() contains a string("report 1" and "report 2") but it wouldnt add it.
Second part of the gif is from Execute_Click event. As you can see, again the messagebox shows that str in stringToConsole() contains a string(whatever i type) and it would add it
Following code is in Class Misc.
Following code's strings are not able to be added.
public static string myFunction()
{
Main myClass = new Main();
myClass.stringToConsole("report 1", "ConsoleList");
Thread.Sleep(2000); // emulate work
myClass.stringToConsole("report 2", "ConsoleList");
return "string";
}
Following codes are inside the form class Main.
private void startupProcedure()
{
label1.Text = Misc.myFunction();
}
This add strings to the ListView(Console List)
public void stringToConsole(string str, string destination)
{
if (destination == "ConsoleList")
{
// to check if str has a value
MessageBox.Show(str); // string does have a value
ConsoleList.Items.Add(str); // refuse to use str from myFunction()
}
}
Following code's strings are able to be added.
private void Execute_Click(object sender, EventArgs e)
{
executeCommandLine(CommandLine.Text, "ConsoleList");
CommandLine.Clear();
}
public void executeCommandLine(string commandLine, string destination)
{
stringToConsole(commandLine, destination); // this shows in Listview
}

A very similar question was asked some hours ago. You have a very, very basic problem:
Main myClass = new Main();
You are instantiating a new Main form, however, you are never showing it or using it outside the function's scope, hence, you are not modifying the Main instance you want to modify.
An easy way to do this would be to pass the Main instance to the function:
public static string myFunction(Main formInstance)
{
formInstance.stringToConsole("report 1", "ConsoleList");
Thread.Sleep(2000); // emulate work
formInstance.stringToConsole("report 2", "ConsoleList");
return "string";
}
private void startupProcedure()
{
label1.Text = Misc.myFunction(this);
}

write text on console and file simultaneously

Guten Tag!
The problem is: I have some code which prints some text messages via Console class on terminal (command line window). I need this info to be placed in two 'containers' - terminal and text file.
Is there a way of adding output stream to Console class in order to make it output data not only on terminal?
It'd be grate if I wont need to change existing code too much (there are a lot of places where Console.Write() and Console.WriteLine() are used).

This is not a full implementation but it should be enough to get you started down the path you seek.
class Program
{
static void Main(string[] args)
{
DualOut.Init();
Console.WriteLine("Hello");
Console.ReadLine();
}
}
public static class DualOut
{
private static TextWriter _current;
private class OutputWriter : TextWriter
{
public override Encoding Encoding
{
get
{
return _current.Encoding;
}
}
public override void WriteLine(string value)
{
_current.WriteLine(value);
File.WriteAllLines("Output.txt", new string[] { value });
}
}
public static void Init()
{
_current = Console.Out;
Console.SetOut(new OutputWriter());
}
}
If you run this code you will see that "Hello" is printed to both the console and to the file "Output.txt"

You can't do it without changing your code. Simply create another class, for example "MyConsole" and add static methods "Write()" and "WriteLine()" to it. Internally call Console.Write() and Console.WriteLine() methods from your created methods. Also call methods that write text to a file from your methods. Then use your MyConsole class instead of Console for output data. Visual Studio Find/Replace feature will help you changing your code.

You should use StreamWriter. It requires minimum additional code.
Follow this example and it will work.
you need to type " using System.IO" in order for this code to work. Don't forget to write it.
the "YourTextFile.txt" needs the .txt.
In order to see the results in you text file, you need to go to the actual folder in your computer, and open the Text file from there. The text file in Visual Studio will appear empty.
( e.g. c:/documents/visualstudio/projects/ConsoleApplication1/bin/debug/YourTextFile.txt)
Solution
First Create a text file YourTextFile.txt in Visual Studio. Then in the Solution Explorer menu to the right, click on YourTextFile in order to see the Properties below the Solution Explorer. Change the property "Copy to Output Directory" from "Do Not Copy" to "Copy Always". (This is an absolute must)
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
namespace ConsoleApplication1
{
class Answer
{
static void Main(string[] args)
{
string text = "This text will appear on your console and be saved in the txt file";
Console.WriteLine(text);
StreamWriter saveText = new StreamWriter("YourTextFile.txt");
saveText.WriteLine(text);
saveText.Close();
Console.ReadLine();
}
}
}
This should do the job. I don't know what your output in the console looks like, but if it is not just one line, and there are multiple Console.Writelines giving output to the console, then you can use while and if, to check every line of the console and if it is not null to write it out. e.g. while (line != null) followed byif (line != null)(assuming you set "line" to equal the output in your console)

I can't get the post by iamkrillin to work.
But the following does work:
class Program
{
static void Main(string[] args)
{
ConsoleFileOutput cf = new ConsoleFileOutput("Output.txt", Console.Out);
Console.SetOut(cf);
Console.WriteLine("0ne");
Console.WriteLine("two");
Console.WriteLine("three");
cf.Close();
}
public class ConsoleFileOutput : TextWriter
{
#region Fields
private Encoding encoding = Encoding.UTF8;
private StreamWriter writer;
private TextWriter console;
#endregion
#region Properties
public override Encoding Encoding
{
get
{
return encoding;
}
}
#endregion
#region Constructors
public ConsoleFileOutput(string filePath, TextWriter console, Encoding encoding = null)
{
if (encoding != null)
{
this.encoding = encoding;
}
this.console = console;
this.writer = new StreamWriter(filePath, false, this.encoding);
this.writer.AutoFlush = true;
}
#endregion
#region Overrides
public override void Write(string value)
{
Console.SetOut(console);
Console.Write(value);
Console.SetOut(this);
this.writer.Write(value);
}
public override void WriteLine(string value)
{
Console.SetOut(console);
Console.WriteLine(value);
this.writer.WriteLine(value);
Console.SetOut(this);
}
public override void Flush()
{
this.writer.Flush();
}
public override void Close()
{
this.writer.Close();
}
#endregion
#region IDisposable
new public void Dispose()
{
this.writer.Flush();
this.writer.Close();
this.writer.Dispose();
base.Dispose();
}
#endregion
}
}

Bind Console Output to RichEdit

So pretty straightforward question. I have a c# .dll with a whole lot of Console.Writeline code and would like to be able to view that output in a forms application using this .dll. Is there a relatively easy way of binding the console output to a RichEdit (or other suitable control)? Alternatively, can I embed an actual console shell within the form? I have found a few somewhat similar questions but in most cases people wanted to be able to recieve console input, which for me is not necessary.
Thanks.

You can use Console.SetOut() to redirect the output. Here's a sample form that demonstrates the approach. Drop a RichTextBox and a button on the form.
public partial class Form1 : Form {
public Form1() {
InitializeComponent();
button1.Click += button1_Click;
Console.SetOut(new MyLogger(richTextBox1));
}
class MyLogger : System.IO.TextWriter {
private RichTextBox rtb;
public MyLogger(RichTextBox rtb) { this.rtb = rtb; }
public override Encoding Encoding { get { return null; } }
public override void Write(char value) {
if (value != '\r') rtb.AppendText(new string(value, 1));
}
}
private void button1_Click(object sender, EventArgs e) {
Console.WriteLine(DateTime.Now);
}
}
I assume it won't be very fast but looked okay when I tried it. You could optimize by overriding more methods.

IMO, it would be better to refactor the existing code, replacing the existing Console.WriteLine to some central method in your code, and then repoint this method, presumably by supplying another TextWriter:
private static TextWriter output = Console.Out;
public static TextWriter Output {
get {return output;}
set {output = value ?? Console.Out;}
}
public static void WriteLine(string value) {
output.WriteLine(value);
}
public static void WriteLine(string format, params string[] args) {
output.WriteLine(format, args);
}
Or (simpler and less hacky re a static field), simply pass a TextWriter into your existing code and write to that?