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Marshal list of objects from VB6 to C #

I have a development that requires transferring objects between a VB6 application and a C # class library. Objects are defined in the C # class library and are used as parameters to methods exposed by other classes in the same library. All objects contain simple string / numeric properties and therefore marshaling was relatively painless.

We now have a request to pass an object containing a list of other objects. If I were coding this in VB6, I could have a class containing the collection as a member variable. In C #, I can have a class with a List member variable.

Is it possible to build a C # class in such a way that a VB6 application can populate this inner list and marshal it successfully? I don't have much experience here, but I would suggest that Id should use an array of object types.

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The options are more limited via COM than you have in C #:



  • You can't use generics (COM doesn't support this, and TLBEXP doesn't use them)

  • There is an old class ArrayList. Or an array.

  • The COM interop layer will automatically generate a COM enumerator for the C # class that implements IEnumerable (non-generic version), you can repeat it on the VB6 side with For Each.

  • Likewise, it generates an IEnumerable for a COM class that implements a COM enumerator. You can use foreach in your C # code to enumerate VB6 Collections. Choose between them depending on who is creating the collection.

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