I know that in Visual Basic, delegate function cannot contain optional parameters. But can a method take a delegate as an optional parameter?
What I want to do is this:
Delegate Sub MyDelegate(ByVal input As String)
Sub MyDelegateDefault(ByVal input As String)
'by default do nothing'
End Sub
Sub MyDelegateCustom1(ByVal input As String)
'do something here'
End Sub
In a different part of code:
Sub OtherFunction(ByVal str As String, Optional ByVal delegate As MyDelegate = AddressOf MyDelegateDefault)
delegate(str)
End Sub
Sub ParentFunction()
OtherFunction("", ) '< "" as string, nothing for optional delegate parameter'
End Sub
Note how the final function OtherFunction
takes a optional delegate as second parameter.
Is this a thing? Can a delegate function be an optional parameter?
A parameter that is of a reference type can only be defaulted to null. Change the default value to null, check for the null condition, and don't call the delegate (do nothing).