I currently have an installation "framework" that does specific things. What I need now to do is be able to call my form in parallel with my script. Something like this:
InstallationForm f = new InstallationForm();
Application.Run(f);
InstallSoftware(f);
private static void InstallSoftware(InstallationForm f) {
f.WriteToTextbox("Starting installation...");
Utils.Execute(#"C:\temp\setup.msi", #"-s C:\temp\instructions.xml");
...
f.WriteToTextbox("Installation finished");
The current way I can do this is by adding the Form.Shown handler in InstallSoftware, but that seems really messy. Is there anyway I can do this better?
Your code will not work, because Application.Run(f) returns not until the form was closed.
You may use a simplified Model/View/Controller pattern. Create an InstallationFormController class that has several events, e.g. for textual notifications to be written to your textbox. The InstallationForm registers on these events in it's OnLoad() method and then calls InstallationFormController.Initialize(). That method starts your installation (on a worker thread/task). That installation callback method fires several text events.
InstallationForm f = new InstallationForm(new InstallationFormController());
Application.Run(f);
internal class InstallationFormController
{
public event EventHandler<DataEventArgsT<string>> NotificationTextChanged;
public InstallationFormController()
{
}
public void Initialize()
{
Task.Factory.StartNew(DoInstallation);
}
private void DoInstallation()
{
...
OnNotificationTextChanged(new DataEventArgsT<string>("Installation finished"));
}
private void OnNotificationTextChanged(DataEventArgsT<string> e)
{
if(NotificationTextChanged != null)
NotificationTextChanged(this, e);
}
}
public class DataEventArgsT<T> : EventArgs
{
...
public T Data { get; set; }
}
internal class InstallationForm : Form
{
private readonly InstallationFormController _controller;
public InstallationForm()
{
InitializeComponent();
}
public InstallationForm(InstallationFormController controller) : this()
{
if(controller == null)
throw new ArgumentNullException("controller")
_controller = controller;
}
protected override void OnLoad(EventArgs e)
{
base.OnLoad(e);
_controller.NotificationTextChanged += Controller_NotificationTextChanged;
_controller.Initialize();
}
protected virtual void Controller_NotificationTextChanged(object sender, DataEventArgsT<string> e)
{
if(this.InvokeRequired)
{ // call this method on UI thread!!!
var callback = new EventHandler<DataEventArgsT<string>>(Controller_NotificationTextChanged);
this.Invoke(callback, new object[] {sender, e});
}
else
{
_myTextBox.Text = e.Data;
}
}
...
}
Related
I want to bubble up a message through classes. I used events and did this:
public class TopLevel{
public event EventHandler<string> Message;
public MiddleLevel mid;
public TopLevel()
{
mid.Message += (s, e) => { Message(s, e) };
}
}
public class MiddleLevel{
public event EventHandler<string> Message;
public BottomLevel bottom;
public MiddleLevel()
{
bottom.Message += (s, e) => { Message(s, e) };
}
}
public class BootomLevel{
public event EventHandler<string> Message;
public void DoSomething()
{
Message?.Invoke(this, "I did it.");
}
}
public class Handler{
public void HandleEvent(TopLevel top)
{
top.Message += PrintMessage;
}
public void PrintMessage(object sender, string message)
{
Console.WrteLine(message);
}
}
Also tried changing constructor to lambda expressions like this:
public class TopLevel{
public event EventHandler<string> Message;
public MiddleLevel mid;
public TopLevel()
{
mid.Message += (s, e) => { Message?.Invoke(s, e); };
}
}
public class MiddleLevel{
public event EventHandler<string> Message;
public BottomLevel bottom;
public MiddleLevel()
{
bottom.Message += (s, e) => { Message?.Invoke(s, e); };
}
}
public class BootomLevel{
public event EventHandler<string> Message;
public void DoSomething()
{
Message?.Invoke(this, "I did it.");
}
}
public class Handler{
public void HandleEvent(TopLevel top)
{
top.Message += PrintMessage;
}
public void PrintMessage(object sender, string message)
{
Console.WrteLine(message);
}
}
Codes above doesn't print any message. Even if I handle event in MiddleLevel class, I still get no message. I assume it is because message call is made in constructor (Even though linq quarries update themselves)? If I handle event in Handle class straight from BottomLevel class, it obviously - works. But I need to bubble the message up, I can't think of any other way to to this, because of how classes are constructed. Is it even possible to do what I have in mind with a standard Eventhandler class? If so than how? Should I just make an event class myself as in one of the sites i refered?
I refered to these sites:
What is the preferred way to bubble events?
https://www.carlosble.com/2016/04/event-bubbling-in-c/
Updated answer:
If you want 'Handler' to be triggered you will have to make sure that 'BottomLevel' falls within the hierarchy of the 'TopLevel' class being passed to the handler, this can be done via dependency injection (DI).
If 'BottomLevel' instantiates it's own classes (no DI) then it will not know about 'Handler', so handler will never be triggered.
If you comment out the DI setup and un-comment the 'BottomLevel' instantiation you can see the different behaviors.
class Program
{
static void Main(string[] args)
{
//setup the classes (dependency injection)
TopLevel topLevel = new TopLevel();
MiddleLevel middleLevel = new MiddleLevel(topLevel);
BottomLevel bottomLevel = new BottomLevel(middleLevel);
//set up the handler
Handler h = new Handler(topLevel);
//using this will not link to 'Handler' as there is no relation between this bottom and top
//BottomLevel bottomLevel = new BottomLevel();
//trigger the bottom class
bottomLevel.TriggerBottom();
//or
bottomLevel.DoSomething(null, "call from main");
Console.ReadLine();
}
}
public class Handler
{
TopLevel _topLevel;
public Handler(TopLevel topLevel)
{
if (topLevel != null)
_topLevel = topLevel;
_topLevel.Message += _topLevel_Message;
}
private void _topLevel_Message(object sender, string e)
{
Console.WriteLine($"handler triggered : {e}");
}
}
public class TopLevel
{
public event EventHandler<string> Message;
public TopLevel()
{ }
public void TriggerTop()
{
Message?.Invoke(this, "origin top");
}
public void DoSomething(object sender, string e)
{
Console.WriteLine($"Do something at top : {e}");
Message?.Invoke(this, e);
}
}
public class MiddleLevel
{
TopLevel _TopLevel;
public event EventHandler<string> Message;
public MiddleLevel(TopLevel topLevel) : this()
{
_TopLevel = topLevel;
}
public MiddleLevel()
{
if (_TopLevel == null)
_TopLevel = new TopLevel();
//subscribe this message to bottom message event method
Message += (s, e) => { _TopLevel.DoSomething(s, e); };
}
public void TriggerMiddle()
{
Message?.Invoke(this, "origin middle");
}
public void DoSomething(object sender, string e)
{
Console.WriteLine($"do something in middle : {e}");
//invoke the event(s)
Message?.Invoke(sender, e);
}
}
public class BottomLevel
{
MiddleLevel _MidLevel;
public event EventHandler<string> Message;
public BottomLevel(MiddleLevel midLevel) : this()
{
_MidLevel = midLevel;
}
public BottomLevel()
{
if (_MidLevel == null)
_MidLevel = new MiddleLevel();
////here you assign it
Message += (s, e) => { _MidLevel.DoSomething(s, e); };
}
public void TriggerBottom()
{
DoSomething(this, "origin bottom");
}
public void DoSomething(object sender, string e)
{
Console.WriteLine($"do something at bottom : {e}");
Message?.Invoke(sender, e);
}
}
I have a developing a c# windows form application and I have a method that exists inside the main form class.
Imagine methodA as part of the main form class.
public void methodA() {
A.someMethod();
B.someMethod();
// some more code
if (someCondition) {
// execute some code
}
// initialize timer and set event handler for timer
// run new thread
}
class A {
someMethod() {...}
}
class B {
someMethod() {...}
}
How would I run tests to test the branch logic of this methodA (isCondition)? since it involves initializing timer and running threads. Can i only verify the logic while doing system test ? I dont think it is possible to mock the timer and threading function.
Thank you !
Of course you can mock the timer. This is by creating a new interface, say, ITimerWrapper and implement it by using the concrete Timer class. Basically a wrapper of the Timer class. Then use that instead of the concrete Timer class you have.
Something in the tune of:
public partial class Form1 : Form
{
private readonly ITimerWrapper _timerWrapper;
public Form1(ITimerWrapper timerWrapper)
{
InitializeComponent();
this._timerWrapper = timerWrapper; // of course this is done via dependency injection
this._timerWrapper.Interval = 1000;
}
private void Form1_Load(object sender, EventArgs e)
{
// now you can mock this interface
this._timerWrapper.AddTickHandler(this.Tick_Event);
this._timerWrapper.Start();
}
private void Tick_Event(object sender, EventArgs e)
{
Console.WriteLine("tick tock");
}
}
public interface ITimerWrapper
{
void AddTickHandler(EventHandler eventHandler);
void Start();
void Stop();
int Interval { get; set; }
}
public class TimerWrapper : ITimerWrapper
{
private readonly Timer _timer;
public TimerWrapper()
{
this._timer = new Timer();
}
public int Interval
{
get
{
return this._timer.Interval;
}
set
{
this._timer.Interval = value;
}
}
public void AddTickHandler(EventHandler eventHandler)
{
this._timer.Tick += eventHandler;
}
public void Start()
{
this._timer.Start();
}
public void Stop()
{
this._timer.Stop();
}
}
Then for the spinning of a new thread, that's also testable by doing the same thing.
Bottomline is to have an interface to separate concerns and mock the interface on your unit test.
I have 3 classes namely Login, Barcode, and the Main.
Login class just contains the authentication of the users.
Barcode class has the following snippet code:
class Barcode
{
public delegate void BarcodeReadHandler(object sender, BarcodeEventArgs e);
public event BarcodeReadHandler BarcodeReadOut;
public Barcode()
{
//.. some codes for getting data on the scanner
BarcodeEventArgs args = new BarcodeEventArgs(scannedData);
BarcodeReadOut(this, args);
}
}
While in Main class, the subsciption of the Barcode event is done:
public partial class Main : Form
{
private Barcode barcode = null;
public Main()
{
barcode.BarcodeReadOut += new barcode.BarcodeReadHandler(getBarcodeStr);
}
//This is called before log-out.
public void removeInstance()
{
barcode.BarcodeReadOut -= new barcode.BarcodeReadHandler(getBarcodeStr);
}
private void getBarcodeStr(object sender, BarcodeEventArgs e)
{
//some code
}
}
The duplication of event subscription happens when I try to logout and login again.
When I tried to debug, BarcodeReadOut is called twice.
In logout, the removeInstance() is called and the Main form is Close() and Dispose() before opening the login screen.
Can someone help me on how can I avoid the duplication of the said events?
I also have done this before registering the event but nothing happens:
public Main()
{
barcode.BarcodeReadOut -= new barcode.BarcodeReadHandler(getBarcodeStr);
barcode.BarcodeReadOut += new barcode.BarcodeReadHandler(getBarcodeStr);
}
You should add and remove the handler as follows:
public partial class Main : Form
{
private Barcode barcode = null;
public Main()
{
barcode.BarcodeReadOut += getBarcodeStr;
}
//This is called before log-out.
public void removeInstance()
{
barcode.BarcodeReadOut -= getBarcodeStr;
}
private void getBarcodeStr(object sender, BarcodeEventArgs e)
{
//some code
}
}
Also: You don't need to define a custom delegate, you can use the generic EventHandler:
public event EventHandler<BarcodeEventArgs> BarcodeReadOut;
It would be good to move all your logic that works with Barcode to a separate class. And it might be good to add a custom event that notifies other classes (a Form class in your case) that event has occurred :
class Barcode
{
public delegate void BarcodeReadHandler(object sender, BarcodeEventArgs e);
public event BarcodeReadHandler BarcodeReadOut;
public Barcode()
{
//.. some codes for getting data on the scanner
BarcodeEventArgs args = new BarcodeEventArgs(scannedData);
BarcodeReadOut(this, args);
}
}
class BarcodeWorker
{
private Barcode barcode = null;
private BarcodeReadHandler handler;
public event BarcodeEventArgs scanComplete;
BarcodeWorker(Barcode barcode)
{
if(barcode == null) this.barcode = barcode;
}
public AddEventHandler()
{
if(handler != null) return;
handler = new BarcodeReadHandler(getBarcodeStr);
barcode.BarcodeReadOut += handler;
}
//This is called before log-out.
public void RemoveEventHandler()
{
barcode.BarcodeReadOut -= handler;
handler = null;
}
private void getBarcodeStr(object sender, BarcodeEventArgs e)
{
scanComplete(sender, e);
}
}
And use it like this:
BarcodeWorker barcode = new BarcodeWorker();
barcode.scanComplete += // your delegate with event handler or with anonymous method here;
In my code for the PluginManager the event PluginEvent gets triggered after
a plugin has been added. But I want to get the event also triggered in the test class.
Somehow I cant solve this problem. The event only gets triggered in the PluginManager class. I read some articles how to create events and so on, but I got even more confused
PluginManager class
public class PluginEventArgs
{
public PluginEventArgs(string s) { Text = s; }
public String Text { get; private set; } // readonly
}
public class PluginManager
{
// Declare the delegate (if using non-generic pattern).
public delegate void PluginEventHandler(object sender, PluginEventArgs e);
// Declare the event.
public event PluginEventHandler PluginEvent;
protected virtual void RaiseSampleEvent(string message)
{
if (PluginEvent != null)
PluginEvent(this, new PluginEventArgs(message));
}
public PluginManager()
{
PluginEvent += PluginManager_PluginEvent;
SomeMethod();
}
void PluginManager_PluginEvent(object sender, PluginEventArgs e)
{
//This event gets triggered =)
}
public void SomeMethod()
{
//Code
RaiseSampleEvent("Name of the Plugin");
//Code
}
}
My test class:
class test
{
public test()
{
PluginManager pluginMg = new PluginManager();
pluginMg.PluginEvent += pluginMg_PluginEvent;
}
//I want this event to get triggered when a new plugin has been found
void pluginMg_PluginEvent(object sender, PluginEventArgs e)
{
MessageBox.Show(e.Text);
}
}
How can I manage to get the event triggered in the test class?
Thanks for any advise!
You're actually doing things right except for one logical Mistake.
In your test class you're creating the PluginManager by using the constructor. The constructor of PluginManager first subscribes to the event and then raises it.
AFTERWARDS you're subscribing to that event.
The simple Problem is that when you are raising the event your test class has not subscribed yet. When you raise that event again everything should work out just fine.
Another thing is that I would use the generic EventHandler class instead of creating your own delegates. This keeps your code cleaner and everyone knows that this is meant to be an event at first glance.
Just inherit PlugInEventArgs from EventArgs and then use EventHandler.
In your PluginManager class you shouldn't subscribe to your own event PluginEvent, you should subscribe to an external event or just raise the PluginEvent.
Let me give you an example:
public class PluginEventArgs
{
public PluginEventArgs(string s) { Text = s; }
public String Text { get; private set; } // readonly
}
public class OtherClass
{
public event PluginEventHandler PluginEvent;
private void RaiseEvent()
{
if (null != PluginEvent)
PluginEvent(this, new PluginEventArgs("some message"));
}
}
public delegate void PluginEventHandler(object sender, PluginEventArgs e);
public class PluginManager
{
public event PluginEventHandler PluginEvent;
private OtherClass otherClass;
protected virtual void RaiseSampleEvent(string message)
{
if (PluginEvent != null)
PluginEvent(this, new PluginEventArgs(message));
}
public PluginManager(OtherClass otherClass)
{
this.otherClass = otherClass;
this.otherClass.PluginEvent += otherClass_PluginEvent;
SomeMethod();
}
void otherClass_PluginEvent(object sender, PluginEventArgs e)
{
if (PluginEvent != null)
PluginEvent(sender, e); // this way the original sender and args are transferred.
}
public void SomeMethod()
{
//Code
RaiseSampleEvent("Name of the Plugin");
//Code
}
}
class test
{
public test()
{
OtherClass otherClass = new OtherClass();
PluginManager pluginMg = new PluginManager(otherClass);
pluginMg.PluginEvent += pluginMg_PluginEvent;
}
//I want this event to get triggered when a new plugin has been found
void pluginMg_PluginEvent(object sender, PluginEventArgs e)
{
MessageBox.Show(e.Text);
}
}
I declare a subscription to event in:
public class MainClass
{
public void btndel_bar_Click(object sender, RoutedEventArgs e)
{
SomeClass sc = new SomeClass();
sc.FieldUpdate += new SomeClass.FieldUpdateHandler(sc_FieldUpdate);
}
void sc_FieldUpdate(object sender, ValueEventArgs e)
{
MessageBox.Show(e.Smth_property);
}
}
And here is I want to listen event:
public class Someclass
{
public delegate void FieldUpdateHandler(object sender, ValueEventArgs e);
public event FieldUpdateHandler FieldUpdate;
void Somemethod()
{
string str = "Steel";
ValueEventArgs args = new ValueEventArgs(str);
FieldUpdate(this, args);
}
}
A class which carries data:
public class ValueEventArgs : EventArgs
{
private string smth;
public ValueEventArgs(string smth)
{
this.smth = smth;
}
public string Smth_property
{
get { return smth; }
}
}
I always have FieldUpdate=null. How to solve it?
You're calling Somemethod() in the constructor, before the calling code gets a chance to add the event handler.
Therefore, the event is still null.
The moment you create the object of SomeClass your event would get reinitialized.
Make your event a static so that multiple objects of SomeClass would share it
public static event FieldUpdateHandler FieldUpdate;
I've read articles about delegates and events and after reading I always I thought to make all operations again. I did all over again and it works! Consequently I done something wrong when I did at the beginning of.