Functional Interface (Runnable) In VBA

This Repository show you how to implement Runnable in VBA. In other programming language(Java,Javascript,Even in Power Query) you can pass code as argument and that code will be used. So Let's say we have a very generic function which do simply like Text Transformation. So you want to take the text and a transformer function which you will use on the text and return that. Now you don't want to hardcode the process about the transformation. You want to give flexibility to the client to pass whatever transformation mechanism they want to use and you want to use that. So if they just simply want to convert it into upper case then they can do that. If they want to do lower case or proper case then they can do that. Your code just depends on the transformer function which can be anything. Or Maybe user wants to do reverse case(Make lower case to upper and upper to lower case) or sentence case. So that's kind of flexibility I am talking about. Our function is very generic function which doesn't depends on solid logic but depends on abstraction. Here come's the Functional Interface(https://www.geeksforgeeks.org/functional-interfaces-java/). You can write code which you can pass and use that.

For simple text it will not be so much useful. As VBA doesn't support Lambda (I am not talking about lambda function from worksheet) that's why this is a good way to have the same kind of behaviour as Lambda would give you. But you have to add some boilerplate code for this.

Use

Let's say you have a list of text(Array) and you want to apply the same transformation for each item then you can just pass the array and this Transformation functional interface instance(Concrete Implementation) and then it will apply for each element.

Example Code

Public Sub ArrayExample()

  Dim InputArray(1 To 2, 1 To 3) As Variant
  InputArray(1, 1) = "Developer: Md.Ismail Hosen"
  InputArray(1, 2) = "Email : 1997ismail.hosen@gmail.com"
  InputArray(1, 3) = "LinkedIn : https://www.linkedin.com/in/md-ismail-hosen-b77500135/"
  InputArray(2, 1) = "Facebook : https://www.facebook.com/mdismail.hosen.7"
  InputArray(2, 2) = "Youtube : https://www.youtube.com/channel/UCL-q7_WvISkw0Ox9FRBBzmw"
  InputArray(2, 3) = "Please contact for any project or VBA Automation."

  Dim Result As Variant
  Result = ApplyTransformationToAll(InputArray, New ProperCaseTransformer)

End Sub

Public Function ApplyTransformationToAll(GivenArray As Variant, TransformerFunction As ITransformer)
    
    Dim FirstColumnIndex  As Long
    FirstColumnIndex = LBound(GivenArray, 2)
    Dim FirstRowIndex As Long
    FirstRowIndex = LBound(GivenArray, 1)
    Dim CurrentRowIndex As Long
    For CurrentRowIndex = LBound(GivenArray, 1) To UBound(GivenArray, 1)
        Dim CurrentColumnIndex As Long
        For CurrentColumnIndex = LBound(GivenArray, 2) To UBound(GivenArray, 2)
            Dim ApplyOnText As String
            ApplyOnText = CStr(GivenArray(CurrentRowIndex, CurrentColumnIndex))
            GivenArray(CurrentRowIndex, CurrentColumnIndex) = TransformerFunction.Apply(ApplyOnText)
        Next CurrentColumnIndex
    Next CurrentRowIndex
    
    ApplyTransformationToAll = GivenArray
    
End Function