I need to pass a reference of a function to another function in VB.NET. How can this be done?
My function needs to use AddHandler internally, for which I need to pass it a handling function. My code below obviously does not work, but it conveys the idea of what I need.
Public Function CreateMenuItem(ByVal Name As String, ByRef Func As AddressOf ) As MenuItem
Dim item As New MenuItem
item.Name = Name
'item. other options
AddHandler item.Click, AddressOf Func
Return item
End Function
Is there another way to do this? The AddHandler needs to be set to a passed parameter in a function somehow...
A function delegate is just what you need to do this. First you need to define the delegate somewhere in the class. Change the signature to fit your event of course.
Your function will take the delegate as an argument.
And here's how you call the function:
First off, event handlers have to have Subs. Secondly,
AddressOf
can't be used as a type. If the sub is in the same class, just use the sub name. If it's in another class/file, you might have to make the sub public and/or qualify it as being a member of the other class. Subs for the AddHandler clause must basically follow the pattern:If you need different routines based on the name of the menu item, you could use one handler and call the appropriate routine based on the name of the item triggering the event.
Your second argument in the function should be of type
EventHandler
, and your function would then look like:Now you need a method to handle those clicks:
And you can consume those two methods now with something like: