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Named Parameters.

Named Parameters., How they make you code more Readable.

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AdamSpeight2008
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11 Mar, 2009 - 06:08 PM

Post #1

I been wondering for a quite a while what VariableName:= was used for when you entering the values of parameter of a subroutine, function or method.
Today I realized what they are used for. So I wrote this tutorial so you can understand them too.

Named Parameters

To explain them, imagine that in your code you have the following routine. (Without using Named Parameters)
I know it's a bit simple but the principles that count in this tutorial

CODE

Private Function Divide(Byval Divider as Double, ByVal Divisor As Double) As Double
' Work out the quotient
Return Divider / Divisor
End Function

And you use it like.

CODE

Dim A As Double =10
Dim B As Double =2
Dim C As Double = Divide(A,B)

Without using Intellisense what A & B are being using for by the Divide Function is a bit hard.
In this example you could probably guess but what if the function was called xyz it is a lot harder.

But by using named parameters it's a lot easier.

CODE

Dim A As Double =10
Dim B As Double =2
Dim C As Double = Divide(Divider:=A,Divisor:=B)

Which is saying;-
The Divide function's Divider parameter is the contents of variable A
The Divide function's Divisor parameter is the contents of variable B

Another Example

CODE

Private Sub PrintHello(ByVal DoYouWantTheHello As Boolean)
  If DoYouWantTheHello =True Then
   Console.WriteLine("Hello World")
  Else
   Console.WriteLine("World")
  End If
End Sub

CODE

PrintHello(DoYouWantTheHello:=True)

Using this alongside with using good variable names makes, in my opinion, the code a lot easier to understand by looking at it.