Controlling recursion inside of an iterative loop

Question

I'm trying to build a property inspector method that iteratively inspects all an objects properties and recursively examines all of the sub-properties of those properties until it either runs out of properties or reaches the max recursion level/depth.

However I am running into an issue in tracking the recursion depth due to the fact that the recursion takes place inside of a iterative loop, therefore each property of an object increments the recursion depth, when it shouldn't, only the next level down should.

Here is my example code:

Dim MaxRecursionLevel As Integer = 10
Dim CurrentRecursionLevel As Integer = 1

Function GetPropertiesWithName(objToSearch as Object, optional nameFilters as String()

dim result as new List(of Object)
If CurrentRecursionLevel > MaxRecursionLevel Then Exit Function
CurrentRecursionLevel = CurrentRecursionLevel + 1

'Iteration of properties
For Each item As PropertyInfo In objToSearch.GetType.GetProperties() 
    if PropertyHasName(nameFilters) Then
        result.Add(item)
        dim subItem as Object = item.GetValue(objToSearch, Nothing)

        'Recursion of Subproperties
        dim subResult as List(of Object) = GetPropertiesWithName(subItem, nameFilters)
        if not subResult is Nothing then result.Addrange(subResult)
    End If
Next
Return result
End Function

How can I accurately track the recursion depth, or is there a better way to go about this?

Where do you actually increase CurrentRecursionLevel?

Alex B.
– Alex B.

2016-02-22 08:06:21 +00:00
Commented Feb 22, 2016 at 8:06 — Alex B.
– Alex B., Commented Feb 22, 2016 at 8:06

Nick Johnson · Accepted Answer · 2016-02-22 07:26:00Z

3

Instead of using a global variable to track recursion, pass in the current recursion level as a parameter to your function. At the top of the function, check if the passed in value exceeds the maximum, and return immediately if it does.

answered Feb 22, 2016 at 7:26

Nick Johnson

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1 Comment

MikeDub Over a year ago

This hasn't worked for what I was trying to do, but I believe it was an issue with the structure of my application, not the solution that is causing this. So i've awarded the answer to the first one in :)

Alex B. · Accepted Answer · 2016-02-22 08:15:19Z

3

In resepect to Nicks answer:

Function GetPropertiesWithName(objToSearch as Object, currentRecusrionLevel as Integer, optional nameFilters as String())
  If currentRecusrionLevel > MaxRecursionLevel Then Return new List(Of Object)
  '...
  For Each item As PropertyInfo In objToSearch.GetType.GetProperties() 
    '...
    Dim subResult as List(of Object) = 
         GetPropertiesWithName(subItem,currentRecusrionLevel + 1, nameFilters)
  '...

answered Feb 22, 2016 at 8:15

Alex B.

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