CODEWITHSUNDEEP
.netvb.netvisual-studio-2010
rawr rang
rawr rang

Reputation: 973

.NET How to handle mutliple events in same handler

I have two objects, A and B, and both object have the same method called Hi. So A.hi will show a messagebox saying "hi I'm A" and B.hi will show a message saying "hi I'm B". They also both have a button that will activate this method.

How do I handle both these events in the same handler?

For example if I did them seperately, I would have this for A.

Private Sub btnHi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHiClassA.Click
   A.hi
End Sub

I want to handle both events in same handler and I was able to do a tedious version with this logic;

Private Sub btnHi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHiClassA.Click, btnHiClassB.Click 
   if sender is btnHiClassA then
      A.hi
   elseif sender is btnHiClassB then
      B.hi
   end if
End Sub

Ideally it would go something like this:

Private Sub btnHi_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnHiClassA.Click, btnHiClassB.Click
   'theObject = sender
   'theObject.hi
End Sub

How would I do this?

Upvotes: 0

Views: 80

Answers (2)

Alex
Alex

Reputation: 636

I'm not fully on to what you're trying to achieve and how you want to do it, but to judge from the way that I get it,

I would use Ctype. Ctype gets an object reference (like the sender) and converts it to a object, like a button. In this way you can get properties of the sender - dynamically. So if you have an Event Handler you can use as many objects to handle as you want.

There are many ways to do this, but I would go with creating a Private Sub.

Private Sub ButtonHi(sender As System.Object, e As System.EventArgs)
    Dim ButtonName As String = CType(sender, Button).Name

    If ButtonName = "ButtonHiA" Then
    Msgbox("Hello World, I'm button A!")
    ElseIf ButtonName = "ButtonHiB" Then
    Msgbox("Hello World, I'm button B!")
    End If
End Sub

As you may see, that sub is no real handler, therefore we must direct an object to it: This you can achieve in different ways, following are two.

Add handler in Form_Load:

Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
    AddHandler ButtonHiA.Click, AddressOf ButtonHi
    AddHandler ButtonHiB.Click, AddressOf ButtonHi
End Sub

Redirect handler on button_click:

Private Sub ButtonHiA_Click(sender As System.Object, e As System.EventArgs) Handles ButtonHiA.Click
    ButtonHi(sender, e)
End Sub

Private Sub ButtonHiB_Click(sender As System.Object, e As System.EventArgs) Handles ButtonHiB.Click
    ButtonHi(sender, e)
End Sub

If this is not what you're after, please clarify it in a comment beneath.

Upvotes: 0

Pieter Geerkens
Pieter Geerkens

Reputation: 11893

Define an interface IHiSender with the method Hi.

Implement IHiSender in all your classes.

Define a sub-class of EventArgs as HiSenderEventArgs with an additional property WhoAmI as type IHiSender.

Upvotes: 1

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