Implementing property must have matching 'ReadOnly' or 'WriteOnly' specifiers

Question

I have an interface defined in an idl file and trying to convert a vb6 project to vb.net.

The conversion created the interop from the tlb of this idl and in vs2010 it complains about the property not being implemented (as shown below). Does anyone have any idea why? I even deleted the implementation and got vs2010 to regenerate the stub and still it errors.

example interface in the idl..

[   uuid(...),
    version(2.0),
    dual,
    nonextensible,
    oleautomation
]
interface IExampleInterface : IDispatch
{
 ...
    [id(3), propget]
    HRESULT CloseDate ([out, retval] DATE* RetVal);
    [id(3), propput]
    HRESULT CloseDate ([in] DATE* InVal);
}

VB.Net class...

<System.Runtime.InteropServices.ProgId("Project1_NET.ClassExample")>
Public Class ClassExample
    Implements LibName.IExampleInterface

    Public Property CloseDate As Date Implements LibName.IExampleInterface.CloseDate
        Get
            Return mDate
        End Get
        Set(value As Date)
            mDate = value
        End Set
    End Property

When posting code, please highlight it and hit the `{}` code button. That lets us see it as code and turns on the syntax highlighting. — Damien_The_Unbeliever, Nov 20 '12 at 07:18
Did you manage to solve this problem? If you did please share it with as and accept your answer. — Panos Rontogiannis, Apr 17 '13 at 14:43

score 2 · Answer 1 · answered Nov 20 '12 at 10:13

2

The DATE argument type is the problem. It is not a DateTime or Date, it is a Double. The declaration is given in the WTypes.h SDK header file, line# 1025 for v7.1:

 typedef double DATE;

So fix your property by declaring it As Double and convert back and forth as needed:

Public Property CloseDate As Double Implements LibName.IExampleInterface.CloseDate
    Get
        Return mDate.ToOADate
    End Get
    Set(value As Date)
        mDate = DateTime.FromOADate(value)
    End Set
End Property

answered Nov 20 '12 at 10:13

Hans Passant

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Firstly thank you for your response. However, changing it to Double didn't help either. – lee23 Nov 20 '12 at 22:48
1

Hmm, that was a pretty solid explanation. Copy the .tlb file to a file sharing service if you need more help. – Hans Passant Nov 20 '12 at 22:59
Perhaps a `` is needed? – Mark Hurd Nov 23 '12 at 02:05

Implementing property must have matching 'ReadOnly' or 'WriteOnly' specifiers

1 Answers1