How to determine size of Object?

[Clunietp]

Hello people

I am attempting to use the COPYMEMORY API function with Objects, and it expects the size of the object I am copying as a parameter. I am not using a string, so LEN or LENB won't work here.

I've searched all over the net and in these archives here, but no answers yet....

Is there anything in VB similar to the C++ sizeof function for OBJECTS? I need the size of my object.

Ultimately, I just need to copy an object. Set NewVar = OldVar just gives me a reference to the original object, I need a copy of it (without resorting to looping through the properties of the old object and assigning them to a new virgin object)

Thanks for your help!


Tom

[Edited by Clunietp on 07-13-2000 at 02:28 AM]

[Anders Englund]

I don't know of a way to get the object size, but couldn't you just write a clone function for it? I'm doing that myself and it works very well, and you don't have the hazzle of messing directly with the memory.

//Anders

[Clunietp]

I tried to write a Clone function like this:

Public Function CloneIt(ByVal TheObject as Object) as Object
    Set CloneIt = TheObject
End Function

I figured if I passed it ByVal, then back again, it would copy it -- but it didn't

Can you show me your clone function?

Thanks Anders

[Clunietp]

Anders' clone function didnt work....

anyone else?

Thanks!

[Sam Finch]

You Can't Copy the Object like that I'm afraid, VB stores an Object as a long, which is a pointer to an array of function pointers, these functions are what make up the object. The Best way to Clone an object is to have a clone function Inside the object, have Friend Property Lets in the Object for every variable in your object, and have a clone property which creates a new instance of itself and uses the Freind properties to set each Variable in the new object

Something like this

Option Explicit


Dim m_Public1 As Long
Dim m_Public2 As Long
Dim m_Internal1 As Long
Dim m_Internal2 As Long
Dim m_Internal3 As Long




Public Property Get Public1() As Long
    Public1 = m_Public1
End Property

Public Property Let Public1(ByVal New_Public1 As Long)
    m_Public1 = New_Public1
End Property


Public Property Get Public2() As Long
    Public2 = m_Public2
End Property

Public Property Let Public2(ByVal New_Public2 As Long)
    m_Public2 = New_Public2
End Property



Friend Property Let Internal1(ByVal New_Internal1 As Long)
    m_Internal1 = New_Internal1
End Property

Friend Property Let Internal2(ByVal New_Internal2 As Long)
    m_Internal2 = New_Internal2
End Property

Friend Property Let Internal3(ByVal New_Internal3 As Long)
    m_Internal3 = New_Internal3
End Property



Public Property Get Clone() As Class1
Dim retval As New Class1

retval.Internal1 = m_Internal1
retval.Internal2 = m_Internal2
retval.Internal3 = m_Internal3
retval.Public1 = m_Public1
retval.Public2 = m_Public2

Set Clone = retval

End Property

if the class contains any internal classes they'll have to have clone methods too, If any of the Classes aren't your own then you're pretty stuck.

What was Anders Clone Function BTW?

[Clunietp]

Thanks Sam, but I don't have access to the class module of the object I am copying, and I need this to work with any type of object.

This seems to work OK for now, but I'm not sure what my max object size could be for any type of object....

CopyMemory ByVal (ObjPtr(rsOriginal)), ByVal (ObjPtr(rsInput)), 1200

[Clunietp]

Anders had a clone function basically what you had...the function was internal to the object I was cloning