Interop and Constants Problem

[Guest]

Hi,

I have built a VB.NET, VS 2005 class library that is exposed to VB6/COM
clients. Everything works as expected except for the fact that Constants
(Const) are NOT being exported to the VB6/COM type library; they are not
visible. I have tried every trick in the book to force .NET constants to be
available to VB6/COM, but to no avail. Enumerators appear correctly, but I
need String (Public Const Test As String = "MyString") type constants as
opposed to the numeric (Integer) type Enumerator members (Test = 5); I have
no choice, I cannot use Enumerators as they only store numeric values.

Is there any way to accomplish this. I basically want to avoid the
VB6/COM developer from having to guess which constant value to use; or if
there were to be a modification, that it would be available immediately.

Can anyone please help?


Regards,

Giovanni

 

[Guest]

Hi,

I have built a VB.NET, VS 2005 class library that is exposed to VB6/COM
clients. Everything works as expected except for the fact that Constants
(Const) are NOT being exported to the VB6/COM type library; they are not
visible. I have tried every trick in the book to force .NET constants to be
available to VB6/COM, but to no avail. Enumerators appear correctly, but I
need String (Public Const Test As String = "MyString") type constants as
opposed to the numeric (Integer) type Enumerator members (Test = 5); I have
no choice, I cannot use Enumerators as they only store numeric values.

Is there any way to accomplish this. I basically want to avoid the
VB6/COM developer from having to guess which constant value to use; or if
there were to be a modification, that it would be available immediately.

Can anyone please help?


Regards,

Giovanni

The solution is not to use constants.

Constants doesn't really exist, that is why they are not exposed in the
COM+ interface. They are just named values, that when used in the code
will be replaced by the actual value.

As the constants are replaced during the compilation, that means that if
you change a constant in a library, you can't just replace the library
dll and expect the changed value of the constant to be used. You have to
recompile all code that is using the constant for the change to take effect.

Create read-only properties instead of the constants. They will be
exposed in the COM+ interface, and all code that uses them will get the
value from the library at run time instead of replacing it during
compilation.

 

[Guest]

Hi Goran,

Thanks for your help. I'll give it a shot. I was heading towards
using readonly properties; I figured it would be the only resort. Thanks
again.

Regards,

Giovanni