Return reference from object function

[e_hobsbawm]

I have to admit that I still not get how things work with references in

VB.

I have an object that looks like:


---- myObjectClass -----
private dim myColl as collection


private sub class_initialize()
set myColl = new collection
end sub


private sub class_terminate()
set myColl = nothing
end sib


private function add(v as variant)
myColl.add(v)
end function


public function initilize(a as string)
dim b as variant
dim i as integer


b = split(a,";")
for i = lbound(b) to ubound(b)
myColl.add b(i)
next


end function
----------------------------------


Now I want to write an object function that returns a reference to a
new myObjectClass, with just some of the elements in myColl. I wrote it

like this


---- myObjectClass -----


public function return_match(a as string) as myObjectClass
dim newObject as new myObjectClass


for each c in myColl
if a > c then newObject.add(c)
next


return_match = newObject


end function
----------------------------------


I now use it like this:


dim full_list as myObjectClass
dim sub_list as myObjectClass


set full_list as new myObjectClass
full_list.initialize("apples;bananas;citrus;dates;figs")
set sub_list = full_list.return_match("c")


-----------------------------------


I think it works, but I have crashes now and then. Does this have
memory problems, since I allocate a new object in return_match but
never free it? If so, how would I go ahead to return the object as a
reference?


Best Regards
Eric

 

[Peter T]

Hi Eric,

There's a lot that doesn't make sense. I started trying to second guess the
objectives but gave up, can't see how it ever worked at all yet alone make
Excel crash. You have typed code direct into the post rather than copying
the original, I suspect typos and/or omissions occurred while doing that.

Regards,
Peter T

 

[e_hobsbawm]

Hi Eric,

There's a lot that doesn't make sense. I started trying to second guess the
objectives but gave up, can't see how it ever worked at all yet alone make
Excel crash. You have typed code direct into the post rather than copying
the original, I suspect typos and/or omissions occurred while doing that.

Regards,
Peter T

Hi Peter,

Sorry for typing code directly (sincerely - I myself hate when people
do that. It's always wrong). This is a scaled-down, tested version
which I copied and pasted.

The idea is that I have objects with data which I have in my own
container class.

This is the data-class:
----------- mySmallObjectClass -------------
Private data_ As String

Public Function setdata(ss As String)
data_ = ss
End Function

Public Function getdata() As String
getdata = data_
End Function
---------------------------------------------------

This is the container-class

---------- myContainerClass -----------------
Dim mySmallObjectList As Collection
Dim name As String

Private Sub Class_Initialize()
Set mySmallObjectList = New Collection
End Sub

Private Sub Class_Terminate()
Set mySmallObjectList = Nothing
End Sub

Public Function setname(ss As String)
name = ss
End Function
Public Function getname() As String
getname = name
End Function
Public Function add(ss As String)
Dim newMySmallObject As New mySmallObjectClass
newMySmallObject.setdata (ss)
mySmallObjectList.add newMySmallObject, ss
End Function

Public Function printout()
Dim ss As mySmallObjectClass
Dim i As Integer
i = 0
For Each ss In mySmallObjectList
i = i + 1
Debug.Print ("Item " & i & " in " & name & ": " & ss.getdata())
Next
End Function

Public Function subcontainer(s As String) As myContainerClass
Set subcontainer = New myContainerClass

Dim ss As mySmallObjectClass

For Each ss In mySmallObjectList
If ss.getdata < s Then subcontainer.add (ss.getdata)
Next

End Function

Public Function item(key As String, val As String)
mySmallObjectList.item(key).setdata (val)
End Function
------------------------------------------------------------------------------

And finally a sub for doing tests:
------------------- MODULE 1 -----------------
Public Sub runtests()
'Fill my container
Dim myContainerObject As myContainerClass
Set myContainerObject = New myContainerClass
myContainerObject.setname ("OrigContainer")
myContainerObject.add ("apple")
myContainerObject.add ("banana")
myContainerObject.add ("citrus")
myContainerObject.add ("dates")
myContainerObject.add ("esparagus")
myContainerObject.add ("figs")
myContainerObject.add ("gherkins")
myContainerObject.add ("hallonberries")

'Print out the members in the container
myContainerObject.printout

'Create a sub-container
Dim subContainerObject As myContainerClass
Set subContainerObject = myContainerObject.subcontainer("d")
subContainerObject.setname ("SubContainer")
subContainerObject.printout

'Now change an object in original container and look if it's
changes in subcontainer
myContainerObject.item "apple", "pear" 'set object data to "pear"
instead of apple
myContainerObject.printout
subContainerObject.printout

End Sub
--------------------------------------------------


So to my problems:
It works as expected, but I am a bit worried since my Excel crashes
every time I shut it down. I would be very happy if someone could say
if my setup with the container class function "subcontainer" returning
a reference is a good idea or not.

I am quite new to VB, but not to OO-programming, so I would like all
help, tips and pointers!

//Eric

 

[Peter T]

In a quick glance I can't see anything obvious wrong, all the objects looks
as if they clear down in an orderly way. Not sure if same applies to your
real life set up if say object ref's to class's are at global level.

You could change a few things along the following lines and see if it makes
any difference.

'Public Function setdata(ss As String)
' data_ = ss
'End Function
'
'Public Function getdata() As String
' getdata = data_ ' why the underscore's
'End Function
Public Property Let propData(ss As String)
'data_ = ss
data = ss
End Property

Public Property Get propData() As String
propData = data ' data_
End Property

use like this

newMySmallObject.propData = ss
ss = newMySmallObject.propData

similarly with functions setname & getname


Public Function printout()
' Dim ss As mySmallObjectClass
Dim i As Long 'Integer
i = 0
' For Each ss In mySmallObjectList
For i = 1 To mySmallObjectList.Count
'i = i + 1
'Debug.Print ("Item " & i & " in " & name & ": " & ss.getdata())
' Debug.Print ("Item " & i & " in " & name & ": " &
mySmallObjectList(i).getdata())
Debug.Print "Item " & i & " in " & name & ": " &
mySmallObjectList(i).propData
Next
End Function

Regards,
Peter T