Lazy Evaluation Example In Visual Basic

(Bad ;-) Example of using LazyEvaluation in a VisualBasic program.

(The objective of this exercise is to show that LazyEvaluation is complex and slow: That you shouldn't use it unless the computation is expensive/difficult, and the result won't be needed in many cases.)

Well, you've shown that it's complex (and maybe slow, got any numbers?) in VB. Since I'm not in a VB shop, what do I care?

I get it: if you take extra steps to avoid adding the numbers, then when you add the numbers you end up taking extra steps.

I suppose what we need now is an EagerEvaluationExampleInHaskell to show that LazyEvaluation is still complex and slow by comparison.

Example taken from the LazyEvaluation page: Compute...

Result = (a + b) + (c + d) + (a + b)

using LazyEvaluation.

Usage:

Dim lLazy   As New clsLazyEvaluation
lLazy.a = a
lLazy.b = b
lLazy.c = c
lLazy.d = d
'   (One normally assumes that there is some "distance" in time and/or code at this point.)
Result = lLazy.Result

Class definition for clsLazyEvaluation:

Option Explicit

'
'   Attributes of the class:
'
Private mintA           As Integer      ' Inputs
Private mintB           As Integer
Private mintC           As Integer
Private mintD           As Integer

Private mblnHaveResult  As Boolean      ' Internal
Private mintResult      As Integer      ' Output

Private Sub Class_Initialize()
    mblnHaveResult = False
End Sub

Public Property Let a(ByVal pintNewValue As Integer)
    mintA = pintNewValue
End Property

Public Property Get a() As Integer
    a = mintA
End Property

Public Property Let b(ByVal pintNewValue As Integer)
    mintB = pintNewValue
End Property

Public Property Get b() As Integer
    b = mintB
End Property

Public Property Let c(ByVal pintNewValue As Integer)
    mintC = pintNewValue
End Property

Public Property Get c() As Integer
    c = mintC
End Property

Public Property Let d(ByVal pintNewValue As Integer)
    mintD = pintNewValue
End Property

Public Property Get d() As Integer
    d = mintD
End Property

Public Property Get Result() As Integer
    If Not mblnHaveResult Then
        mintResult = (mintA + mintB) + (mintC + mintD) + (mintA + mintB)
        mblnHaveResult = True
    End If
    Result = mintResult
End Property

Very interesting, but why do your values come in pints and why are you growing mint? mint = member int, pint = parameter int

CategoryLazyPattern