Reference argument in a .NET class library

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I have written a large .NET class library in C++ (using old syntax). It works very well and has been in use with C++, C# and Visual Basic for a while.

Anyway, I just discovered that any method taking an argument that is a reference to a base type is not exposed to Visual Basic.

Let the C++ declaration be

C++

void mVizNET::Histogram::Range(int& Minimum, int& Maximum);

The C++ object browser shows it as

C++

System.Void Range(System.Int32 Minimum, System.Int32 Maximum)
    Member of mVizNET.Histogram

(strangely, the ref keyword is missing).

The C# object browser shows it as

C#

public static void Range(int* Minimum, int* Maximum)
    Member of mVizNET.Histogram

(strangely, the argument is passed as a pointer).

But the Visual Basic object browser does not show it at all :(

Has anyone an explanation ? Is there a special attribute I should give those reference arguments to better expose them ? Is this feature unavailable using the old syntax ? Is it supported in the new syntax ?

Posted 22-Sep-13 22:05pm

YvesDaoust

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YvesDaoust · Accepted Answer · 2013-09-22T23:52:00

I have found a workaround. References can be traded for pointers, provided you use a .NET type instead of a native one.

If you change the prototype to

void mVizNET::Histogram::Range(Int32* Minimum, Int32* Maximum);

then the method appears as

System.Void Range(System.Int32 Minimum, System.Int32 Maximum)
    Member of mVizNET.Histogram

C#

public void Range(ref int Minimum, ref int Maximum)
    Member of mVizNET.Histogram

VB

Public Sub Range(ByRef Minimum As Integer, ByRef Maximum As Integer)
     Member of: mVizNET.Histogram

which is what I need. (Actually, the C++ browser also shows a mVizNET.Histogram.Range(System.Int32@, System.Int32@) declaration, where the @ possibly stands for a C++/CLI reference).

Note that a declaration with references like

void mVizNET::Histogram::Range(Int32& Minimum, Int32& Maximum);

will also work, but is not recognized by the C# browser this time!