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CWizard

[Visual Basic] Copy objects

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I''m a bit confused with VB''s references. I''m in need of copying an object, and as I figure, VB will only work with references, and I''m unable to find a way to give my classes a copy constructor . To illustrate, say I have a class T, with a "property" a, and I do like this
Dim x As New T
Dim y As New T
 
x.a = "1"
Set y = x     // Obviously wrong
y.a = "2"
Now, both x.a and y.a equals "2". No wonder, as they both are referencing the same object. My question is how do I copy objects in a similar manner. I would like to avoid having to instantiate the new object and manually copy each member, as this particular object contains other objects that conatin other object (and so forth).

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As far as I know, the only way to do it is to write your own Copy function that creates a new instance of the class and sets the values as you want them.

SampleClass:


  
Public A As Integer
Public B As Integer

Public Function Copy() As SampleClass
Dim newobject As New SampleClass
newobject.A = Me.A
newobject.B = Me.B
Set Copy = newobject
End Function


Usage:


  
Dim x As SampleClass
Dim y As SampleClass
Set x = New SampleClass
x.A = 1
x.B = 1
Set y = x.Copy
y.A = 2
MsgBox x.A
MsgBox y.A

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Implement a Clone() member function:


  
'' BEGIN MyClass.cls
Public x as Integer
Public y as Integer
Public z as Integer

Public Function Clone() as MyClass
Dim newObj as New MyClass
newObj.x = x
newObj.y = y
newObj.z = z
Set Clone = newObj
End Function

'' END MyClass.cls

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