CODEWITHSUNDEEP
vbaclassoopexcel
colinwurtz
colinwurtz

Reputation: 723

Problems Copying Custom Class

Similar question to How do I to create a copy of a custom object or collection?, but I can't get the solution to work for me. I have 3 related custom classes and having problems copying values from one instance of a class to another. I created Clone methods in each class to specifically create new instances to avoid multiple variables simply pointing to the same object. Here are my classes

class_stat:

Public value As Double
Public name As String
Public flagged As Boolean
Public category_name As String

Public Function Clone_Stat() As class_stat
    Dim stat As class_stat
    Set stat = New class_stat
    stat.name = Me.name
    stat.category_name = Me.category_name
    stat.flagged = Me.flagged
    stat.value = Me.value
    Set Clone_Stat = stat
End Function

class_cat:

Public name As String
Public stats As Collection
Private Sub Class_Initialize()
    Set stats = New Collection 
End Sub

Private Function AddStat(ByRef stat As class_stat)
    stats.Add stat
End Function

Public Function Clone_Cat() As class_category
    Dim cat As class_category
    Set cat = New class_category
    'Copy the cat name
    cat.name = Me.name
    Dim stat As class_stat

    'Copy all the stats
    For Each stat In Me.stats
        cat.stats.Add (stat.Clone_Stat)
    Next stat
    Set Clone_Cat = cat
End Function

class_user:

Public username As String
Public name As String
Public categories As Collection

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

Private Function AddCategory(ByRef category As class_category)
    categories.Add category
End Function

Public Function Clone_User() As class_User
    Dim user As class_User
    Set user = New class_User
    Dim cat As class_category

    'Set values
    user.name = Me.name
    user.username = Me.username

    'Copy over the categories
    For Each cat In Me.categories
        user.categories.Add (cat.Clone)
    Next cat
    Set Clone_User = user
End Function

I'm able to copy one instance a class to another like this:

Dim temp_cat As class_category
Set temp_cat = New class_category
Dim temp_cat1 As class_category
Set temp_cat1 = New class_category
temp_cat1.name = "cat name"
Set temp_cat = temp_cat1.Clone_Cat
temp_cat.name = "cat name" 'Resets temp_cat name without affecting temp_cat1

However when I add a class_stat to class_category and try to copy it throws an error.

Dim temp_stat1 As class_stat
Set temp_stat1 = New class_stat
Dim temp_stat As class_stat
Set temp_stat = New class_stat

Dim temp_cat as class_category
Set temp_cat = New class_category
Dim temp_cat1 As class_category
Set temp_cat1 = New class_category

'Clone some stats fine - this works
temp_stat1.name = "stat name"
Set temp_stat = temp_stat1.Clone_Stat
temp_stat1.name = "stat1 name"

'Clone a cat with no stats - works
temp_cat1.name = "cat name"
Set temp_cat = temp_cat1.Clone_Cat
temp_cat1.name = "cat1 name"

'Try and add stats to temp_cat1 and clone and then it fails
Call temp_cat1.stats.Add(temp_stat.Clone_Stat) 'this works

Dim cloned_cat As class_category
Set cloned_cat = New class_category
Set cloned_cat = temp_cat1.Clone_Cat

The last line above throws the "Object doesn't support this property or method error." When I step through the debug it throws it after getting to the end of the Clone_Stat function. Any ideas on what I'm doing wrong?

Upvotes: 1

Views: 142

Answers (1)

David Zemens
David Zemens

Reputation: 53653

I run this procedure:

Sub TestClones()

Dim temp_cat As class_category
Set temp_cat = New class_category
Dim temp_cat1 As class_category
Set temp_cat1 = New class_category
Dim temp_stat1 As class_stat
Set temp_stat1 = New class_stat
Dim temp_stat As class_stat
Set temp_stat = New class_stat
'Clone some stats fine - this works
temp_stat1.name = "stat name"
Set temp_stat = temp_stat1.Clone_Stat
temp_stat1.name = "stat1 name"

'Clone a cat with no stats - works
temp_cat1.name = "cat name"
Set temp_cat = temp_cat1.Clone_Cat
temp_cat1.name = "cat1 name"

'Try and add stats to temp_cat1 and clone and then it fails
Call temp_cat1.stats.Add(temp_stat.Clone_Stat) 'this works

Dim cloned_cat As class_category
Set cloned_cat = New class_category
Set cloned_cat = temp_cat1.Clone_Cat()

End Sub

I get the same error you do.

Why the error?

There is no default property for this collection, and when you put the parentheses around it, it is attempting to evaluate that expression, which raises the error.

Resolution

Remove the parentheses from this line:

cat.stats.Add (stat.Clone_Stat)

So that you end up with this instead

cat.stats.Add stat.Clone_Stat

I also notice that in your Clone_User you have a mistake -- perhaps it is a typo but you do not have a .Clone method and I think this should be like so for the same reason:

user.categories.Add cat.Clone_Cat

Upvotes: 1

Related Questions