C# Interface methods gets wrong prototype when using COM interop

[kli]

I have a very peculiar problem. I have a c# class library that a access
from a C++ MFC client through COM introp. This work almost well. One
special interface method is translated wrong when exporting to a .tlb
file and importing it into the client app.

The C# interface method snippet:
namespace Scandpower.pt.GridGenerator.Geometry
{
public interface IPipe
{
double Angle(Constants.ANGLETYPE type);
}
}

is when viewing the .tlb file changed to:

IPipe::angle(ByVal type As ANGLETYPE) As Double

As you see the method has the small caps intead of big. This shouldn't
be a big problem, but when my collegue is compiling the same code on
his machine the .tlb file is correct!!

I've used the .dll created a from his machine and used tlbexp on it.
Then the .tlb is correct for me as well. So it seems like a C# compiler
issue. Any localization stuff or other "hidden" settings that can
produce this kind of error?

best,
Kjetil.

 

[Tom Kearney]

I've got the same problem with methods called Id() ..... they get converted
to id() ....

A bit of a pain!!!

Tom Kearney

 

[Mattias Sjögren]

I've got the same problem with methods called Id() ..... they get converted
to id() ....

A common reason for this problem is explained in this KB article

BUG: MIDL Changes the Case of Identifier in Generated Type Library
http://support.microsoft.com/kb/q220137/

Note that the bug is in OleAut. MIDL is just a frontend, and so is
TlbExp.

I don't know if this explains Kjetil's issue though, since this should
be consistent across machines if compiling the same typelib.


Mattias

 

[kli]

Thanks Mattias!
You put me on the right track.
Even though my problem isn't related to the MIDL compiler, but C#
compiler, the cause of the problem seems to be the same. I have another
method in another namespace and interface:
int IGeoGenerator::AddAngleClass(double angle);
when I changed it to:
int IGeoGenerator::AddAngleClass(double i_dAngle);
I got the correct signature on my
IPipe::Angle method.

Although I was somewhat abashed by the status comment in the article!!:
Quote:
STATUS
This behavior is by design.

best,
Kjetil.

Mattias Sjögren skrev: