Question

I came across the following code recently and would like to optimize it:

Public Shared Function ComputeLabel(ByVal Action As Integer, ByVal Flag1 As Boolean, ByVal Flag2 As Boolean) As String
   Dim Prefix As String = ""

   If Flag2 Then
      Prefix = "Conditional "
   ElseIf Flag1 Then
      Prefix = "Held "
   End If

   Select Case Action
      Case 0
         Return ""
      Case 1
         Return Prefix & "Cancelled"
      Case 2
         Return Prefix & "Discontinued"
      Case 3
         Return Prefix & "Suspended"
      Case 4
         Return Prefix & "Unsuspended"
      Case 6
         Return Prefix & "Collected"
      Case 7
         Return Prefix & "Released from Hold"
      Case 8
         Return Prefix & "Modified"
      Case 9
         Return Prefix & "Discontinued for the Future"
      Case 10
         Return Prefix & "Verified"
      Case 11
         Return Prefix & "Modified And Verified"
      Case 12
         Return "Hold " & Prefix & "Cancelled"
      Case Else
         Return ""
   End Select
End Function

Note that Action 0 is the most common case.

Okay, I’ve already cleaned up this function a bit–it was using a variable and returning it at the end, and using Return seems better. But additionally, I think it would be better code to build an array at the beginning of the report execution, and then just access array elements each time this function is called, instead of using a Select statement. But case 12 is making things more complicated (as you can see, it adds the prefix in the middle instead of at the beginning.)

What do you think would be the best way:

• One time building a 39-element array for the three cases:

  Private Shared OrderActions() As String = {"", "Cancelled", ...}
  

  Then in the function accessing it like so:

  If Action < 0 OrElse Action >= 13 Then Return ""
  Return OrderActions(Action - Flag2 * 13 - (Flag1 AndAlso Not Flag2) * 26)
  

• Using a 13-element array with a Replace (something like Return Replace(LabelList(Action), "{Prefix}", Prefix)?)

• Using a 12-element array with a special case for Action 12.

• Something else I haven’t thought of.

?

Update 1: my formatting was off so the options might have been unclear. It should be more readable now.

Update 2: I see what you mean that from a performance perspective, fully expanding all the cases and using simple variable assignment is probably fastest. So… let’s say top speed is not the priority, but overall elegance is (a combination of clean code and speed). Any chance people could give their take on that, too? I’ll vote everyone up who gives reasonable help for all aspects of the question.

Update 3: One additional consideration I was ignoring is that some non-experienced programmers are going to be maintaining this long-term, so it does need to be easy to understand. I guess my examples of trying to shorten the code really aren’t good from this perspective.

Update 4: TESTING IS KING OVER ALL!!! Once I was inspired to do some speed tests, I got some interesting results. See my answer below.

Answer 1

actually, if you put them into arrays, it brings the execution time from 6589ms on my machine to 1174ms using the following method:

Below is from a console app, but you get the general idea. The arrays are loaded once, then accessed as many times as you want, in this case I was using the for loop that Steve Wortham posted as a test.

Dim _ConditionalLabels(12) As String
Dim _HeldLabels(12) As String

Sub Main()
    Dim sw As New Stopwatch()
    sw.Start()

    _ConditionalLabels(0) = ""
    _ConditionalLabels(1) = "Conditional Cancelled"
    _ConditionalLabels(2) = "Conditional Discontinued"
    _ConditionalLabels(3) = "Conditional Suspended"
    _ConditionalLabels(4) = "Conditional Unsuspended"
    _ConditionalLabels(6) = "Conditional Collected"
    _ConditionalLabels(7) = "Conditional Released from Hold"
    _ConditionalLabels(8) = "Conditional Modified"
    _ConditionalLabels(9) = "Conditional Discontinued for the Future"
    _ConditionalLabels(10) = "Conditional Verified"
    _ConditionalLabels(11) = "Conditional Modified And Verified"
    _ConditionalLabels(12) = "Hold Conditional Cancelled"

    _HeldLabels(0) = ""
    _HeldLabels(1) = "Held Cancelled"
    _HeldLabels(2) = "Held Discontinued"
    _HeldLabels(3) = "Held Suspended"
    _HeldLabels(4) = "Held Unsuspended"
    _HeldLabels(6) = "Held Collected"
    _HeldLabels(7) = "Held Released from Hold"
    _HeldLabels(8) = "Held Modified"
    _HeldLabels(9) = "Held Discontinued for the Future"
    _HeldLabels(10) = "Held Verified"
    _HeldLabels(11) = "Held Modified And Verified"
    _HeldLabels(12) = "Hold Held Cancelled"

    Dim str As String = ""
    For i As Integer = 0 To 10000000
        str = ComputeLabel(0, True, False)
        str = ComputeLabel(1, False, False)
        str = ComputeLabel(0, False, False)
        str = ComputeLabel(2, False, False)
        str = ComputeLabel(1, False, True)
        str = ComputeLabel(2, True, True)
        str = ComputeLabel(4, False, True)
        str = ComputeLabel(7, True, True)
        str = ComputeLabel(12, False, True)
    Next

    sw.Stop()
    Console.WriteLine(sw.ElapsedMilliseconds & " ms")
    Console.Read()
End Sub

Public Function ComputeLabel(ByVal Action As Integer, ByVal Held As Boolean, ByVal Conditional As Boolean) As String
    If Conditional Then
        Return _ConditionalLabels(Action)
    ElseIf Held Then
        Return _HeldLabels(Action)
    End If
End Function