RaiseEvent from VB.net to CSharp problem

[mansonho]

RaiseEvent from VB.net to CSharp problem

I am converting my vb.net project to CSharp, everything work fine except the RaiseEvent. I totally have no idea how to do it, can anybody help me?
Thank so much.

I have a custom button control and following is part of the code:

Public Class EnquiryButton
    Inherits System.Windows.Forms.Button

    Public Event EnquiryReturned(ByVal sender As Object, ByVal e As System.EventArgs)
    Private Event ReturnObjectChanged(ByVal sender As Object, ByVal e As System.EventArgs)


    Private Sub BindReturnObjectToTargetControl()
        ' Assign Values to Control
        If Not Me.ReturnValue_TargetControl Is Nothing Then
            CallByName(Me.ReturnValue_TargetControl, Me.ReturnValue_TargetControlPropertyName, CallType.Set, Me.ReturnObject.ReturnValue)
        End If
        If Not Me.ReturnDescription_TargetControl Is Nothing Then
            CallByName(Me.ReturnDescription_TargetControl,   Me.ReturnDescription_TargetControlPropertyName, CallType.Set, Me.ReturnObject.ReturnDescription)
        End If

    End Sub


    Protected Overrides Sub OnClick(ByVal e As System.EventArgs)
        Dim retObj As Enquiry.ReturnObject = FetchReturnObject(Type)
        If Not retObj Is Nothing Then
            _ReturnObject = retObj
            OnReturnObjectChanged(System.EventArgs.Empty)
        End If
        OnEnquiryReturned(System.EventArgs.Empty)
        MyBase.OnClick(e)
    End Sub


    Protected Sub OnReturnObjectChanged(ByVal e As EventArgs)
        BindReturnObjectToTargetControl()
        RaiseEvent ReturnObjectChanged(Me, System.EventArgs.Empty)
    End Sub

    Protected Sub OnEnquiryReturned(ByVal e As EventArgs)
        RaiseEvent EnquiryReturned(Me, System.EventArgs.Empty)
    End Sub

End Class

[mansonho]

Sorry, forgot to post my .net version

my .net version v4.0.30319

VS 2008 Express

Thank

[David Anton]

Just drop the 'RaiseEvent' keyword.

Note that 'CallByName' is not available in C# unless you set a reference to the Microsoft.VisualBasic assembly.

[TheGreatCthulhu]

C# doesn't use a special keyword to raise an event - it just treats it as if it were a delegate.

So, the C# equivalent to

    Protected Sub OnReturnObjectChanged(ByVal e As EventArgs)
        BindReturnObjectToTargetControl()
        RaiseEvent ReturnObjectChanged(Me, System.EventArgs.Empty)
    End Sub

would be

protected void OnReturnObjectChanged(EventArgs e)
{
    BindReturnObjectToTargetControl();
    ReturnObjectChanged(this, System.EventArgs.Empty);
}

However, with the earlier version of the framework, a good practice was to check if there are any methods subscribed to the event before raising it, and although I think I read somewhere that this is no longer necessary, I'm not sure - so the compete version would be:

protected void OnReturnObjectChanged(EventArgs e)
{
    BindReturnObjectToTargetControl();
    
    if(ReturnObjectChanged != null)
        ReturnObjectChanged(this, System.EventArgs.Empty);
}

I'm a bit curious though: why are you converting from VB.NET to C#? Your .NET code should be able to work with pretty much any other .NET language. If this is a DLL, you can reference it from a C# project.

EDIT: ninja'd

[mansonho]

Hi David, TheGreatCthulhu

Thank very much for your reply.

Actually, I don't know why the event is add here, since there is not handler method for the event.
And how can I instantiate it in CSharp without the handler method?
Can you explain?

Thank.

For the CallByName problem, I use Reflection to solve it.

[TheGreatCthulhu]

Actually, I don't know why the event is add here, since there is not handler method for the event.

If I understood your question well, you're asking why the code has the OnReturnObjectChanged() method?
If so, it's simple - it's true that this is not a handler, this is the method that is used to raise the corresponding event. The class that contains it is the only one that "knows" when it's appropriate to raise the event, and it uses this method to do so, and also to perform some additional processing.

Look what OnClick() does:

        Dim retObj As Enquiry.ReturnObject = FetchReturnObject(Type)
        If Not retObj Is Nothing Then
            _ReturnObject = retObj
            OnReturnObjectChanged(System.EventArgs.Empty)
        End If

And how can I instantiate it in CSharp without the handler method?
Can you explain?

VB.NET is a .NET language. All .NET code compiles to the same Intermediate Language (IL) code, no matter in what high-level language it was written. This IL is then, at appropriate time, compiled by the .NET runtime into a platform specific format. This enables two things: (1) code written in any .NET language can cooperate (VB.NET code can work with C# code or C++/CLI code, and vice versa), more or less without the need to make any modifications; and (2) any .NET application is portable to any platform that has some form of .NET runtime installed (for example, it can run on Mono, an open source implementation of Common Language Runtime (CLR) for Linux, Windows, and Mac OS X).

Basically, all you need to do is to add a reference to your VB assembly as you would do with any other .NET assembly. Usually, some of these references are added automatically by the IDE, based on your project type, but it's not hard to add them yourself.

In C#, expand the Solution Explorer tree, and right-click on References, then choose "Add Reference...". When the window shows up, go to the Browse tab, and navigate to your assembly (an .exe or, preferably a .dll file, created from your VB.NET code).

Now you can use all the publicly exposed types in that assembly, the same way you use all other .NET types (remember, the whole .NET library is just a bunch of DLLs).

You'll also want to add the using directives at the top of your .cs file:

using Whatever.VB.Namespace.YouDefined;