Pass a delegate in parameter

Question

I have

Function Bar(s As String) ...

I need to create a function

Me.Foo(myInt, AddressOf Bar)

How should I write the Foo's signature?

samjudson · Accepted Answer · 2012-07-23 15:53:26Z

2

Use of the generic Func(Of Type) keyword is probably the easiest.

Public Function Foo(i As Integer, f As Func(Of String, Integer)) As String
    Dim i2 = f.Invoke("test")
    Return "42"
End Function

answered Jul 23, 2012 at 15:53

samjudson

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Community · Accepted Answer · 2017-05-23 12:13:18Z

1

This may help you

Declare your delegate signature:

Public Delegate Sub Format(ByVal value As String)

Define your Test function:

Public Sub CheckDifference(ByVal A As Integer, _
                           ByVal B As Integer, _
                           ByVal format As Format)
    If (B - A) > 5 Then
        format.Invoke(String.Format( _
        "Difference ({0}) is outside of acceptable range.", (B - A)))
    End If
End Sub

Somewhere in your code call your Test function:

CheckDifference(Foo, Bar, AddressOf log.WriteWarn)

Or

CheckDifference(Foo, Bar, AddressOf log.WriteError)

edited May 23, 2017 at 12:13

CommunityBot

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answered Jul 23, 2012 at 15:43

Phil Murray

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1 Comment

serhio Over a year ago

should I really declare a Public Delegate for each king of function call like this, even if I don't use them?

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