asked on

How to implement a recursive code

Hi,

I have the follwing object say

oReport

and each object has a parent which I can find from the info property like following

oReport.Info.Parent

now think like a folder structure in windows you store a word file in a folder which can reside into some other folder

so the word file is oReport and then the folder in which it is kept is

oReport.Info.Parent

now my goal is to traverse all the parents of an object like this untill the parent becomes null

oReport.Info.Parent
oReport.Info.Parent.Info.Parent.Info
oReport.Info.Parent.Info.Parent.Info.Parent.Info

I need to this for the following reason of the business logic. A report can be considered hidden if the following things are true

oReport.Info.Hidden=true or any of its parent is hidden so I need to loop through all the parents of the report recursivley untill the parent is null and find out if the report is hidden or one of its parents is hidden.

Hope I am clear enough

ASKER CERTIFIED SOLUTION

kaufmed

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SOLUTION

Mike Tomlinson

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kaufmed

Indeed. I guess my brain is starting to fry from staring at code all day ;)

zorvek (Kevin Jones)

Recursive code is not necessary but is a great example of how to use objects. Here is how I would implement a recursive solution using classes. Note that I did not implement an Info class, just the Report class.

The Report class code:

Option Explicit

Public Parent As clsReport

Private mHidden As Boolean

Public Property Get Hidden() As Boolean
If mHidden Then Hidden = True
If Not Parent Is Nothing Then
If Parent.Hidden Then Hidden = True
End If
End Property

Public Property Let Hidden(ByVal NewValue As Boolean)
mHidden = NewValue
End Property

A test routine:

Public Sub Test()

Dim X As clsReport

Set X = New clsReport
Set X.Parent = New clsReport
Set X.Parent.Parent = New clsReport
Set X.Parent.Parent.Parent = New clsReport
Set X.Parent.Parent.Parent.Parent = New clsReport

Debug.Print X.Hidden

X.Parent.Parent.Parent.Hidden = True

Debug.Print X.Hidden

End Sub

Kevin

Amit

ASKER

Hi Kaufmed,

You are correct, as soon as it finds that one of the parent is hidden then the object should be classified as hidden

So you can implement it like this also.

Stop processing as soon as a hidden parent is found

thanks
-anshu

Amit

ASKER

Hi idle mind,

How would you implement it using a while loop ?

thanks
-anshu

Amit

ASKER

I am getting a compile error when I implement the recursive code

Function HasHiddenAncestor(ByRef objReport As IDSSReportDefinition) As Boolean
Dim result As Boolean

If objReport Is Nothing Then
result = False
Else If objReport.Info.Hidden then
result = True
Else
result = HasHiddenAncestor(objReport.Info.Parent)
End If

Return result
End Function

the error is following and it happens at this line of the code

Else If objReport.Info.Hidden then

---------------------------
Microsoft Visual Basic
---------------------------
Compile error:

Must be first statement on the line
---------------------------
OK Help
---------------------------

Mike Tomlinson

Something like:

oReport.Info.Hidden = False ' Assume it's not hidden until proven otherwise
Dim curReport As Report = oReport.Info.Parent
While Not IsNothing(curReport)
If curReport.Info.Hidden Then
oReport.Info.Hidden = True ' Found one! Set the flag on the original instance and exit the loop...
Exit While
End If
curReport = curReport.Info.Parent
End While

SOLUTION

zorvek (Kevin Jones)

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kaufmed

Too much .NET for me I think!

Good call zorvek :D