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Why are virtual methods considered early bound?


Why are virtual methods considered early bound?

By : simquat
Date : October 28 2020, 04:55 PM
hope this fix your issue Late Binding
With late binding all you have is the name of the method. At compile time you have no way of known if the method even exists. This is known as "duck typing" in languages such as Ruby or Python.
code :


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Are override methods considered virtual methods?

Are override methods considered virtual methods?


By : Stefan Conradie
Date : March 29 2020, 07:55 AM
wish help you to fix your issue From §1.6.6.4 Virtual, override, and abstract methods of the C# 4.0 specification (you were quoting an older version):
Is an early bound interface and a late bound implementation possible with C#

Is an early bound interface and a late bound implementation possible with C#


By : user3124753
Date : March 29 2020, 07:55 AM
To fix this issue The most obvious explanation for the problem you describe is that the interface type IInterfaceProcessor you use in your DLL when declaring the type that implements the interface is not the same interface type (also named IInterfaceProcessor) you use in your program when you try to create the instance.
I.e. the Activator.CreateInstance() actually returns a non-null reference (as it always will, unless an exception is thrown), but that type does not implement the interface you are trying to cast it to with the as operator.
On Windows, with a C# authored COM server, can one return a SAFEARRAY both for early bound and late bound code?

On Windows, with a C# authored COM server, can one return a SAFEARRAY both for early bound and late bound code?


By : Guru Kathir
Date : March 29 2020, 07:55 AM
To fix the issue you can do I did a bit of testing on this by marshaling the returned value in to a Variant, and then dumped the memory of the returned VARIANT structure to see what the VARTYPE was. For the early bound call, it was returning a Variant with a VARTYPE of VT_ARRAY & VT_DISPATCH. For the late bound call, it was returning a VARTYPE of VT_ARRAY & VT_UNKNOWN. Apples should already be defined as implementing IDispatch in the tlb, but for some reason that eludes me, VBA is having difficulty handling an array of IUnknown from the late bound call. The work-around is to change the return type to object[] on the C# side...
code :
public object[] enumerateApples()
{
    List<object> applesList = new List<object>();

    //* Add some apples - well, one in fact for the time being 
    Apples app = new Apples();
    app.variety = "Braeburn";
    app.quantity = 4;
    applesList.Add(app);

    // * finished adding apples want to convert to SAFEARRAY 
    return applesList.ToArray();
}
Sub TestEarlyBound()
    'Tools -> References to type library LateBoundSafeArraysProblem.tlb
    Dim fc As LateBoundSafeArraysProblem.FruitCounter
    Set fc = New LateBoundSafeArraysProblem.FruitCounter

    Dim apples As Variant
    apples = fc.enumerateApples()

    Debug.Print apples(0).variety   'prints "Braeburn"
End Sub

Sub TestFruitLateBound0()
    Dim fc As Object
    Set fc = CreateObject("LateBoundSafeArraysProblem.FruitCounter")

    Dim apples As Variant
    apples = fc.enumerateApples()

    Debug.Print apples(0).variety   'prints "Braeburn"
End Sub
Can a C++ class without any pure virtual methods be considered abstract?

Can a C++ class without any pure virtual methods be considered abstract?


By : GaanaBol
Date : March 29 2020, 07:55 AM
like below fixes the issue My understanding is that abstract classes must have one or more pure virtual methods. ,
abstract classes must have one or more pure virtual methods.
code :
class B {
  virtual void foo() = 0;
}
Is method overriding (without virtual methods or pointers) considered a part of Polymorphism?

Is method overriding (without virtual methods or pointers) considered a part of Polymorphism?


By : Murid A Bdii
Date : March 29 2020, 07:55 AM
like below fixes the issue
But since the first program produces the exact same results by overriding the function area, is it considered to be using polymorphism too?
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