Is there a way to share an enum definition between native (unmanaged) C++ and (managed) C#?
I have the following enum used in completely unmanaged code:
Thanks for sharing!
I played around a bit and found a way to have multiple enum and constant declarations without having tons of extra lines :)
// This is a valid C, C++ and C# file :)
#if __LINE__
#define public
#else
namespace MyCSharpNamespace{
#endif
public enum MyConstant { MaxStr = 256 };
public enum MyEnum1{ MyEnum1_A, MyEnum1_B };
public enum MyEnum2{ MyEnum2_A, MyEnum2_B };
#if __LINE__
#undef public
#else
}
#endif
Remember to name your file *.cs
You can use a single .cs file and share it between both projects. #include
in C++ on a .cs file should be no problem.
This would be an example .cs file:
#if !__LINE__
namespace MyNamespace
{
public
#endif
// shared enum for both C, C++ and C#
enum MyEnum { myVal1, myVal2 };
#if !__LINE__
}
#endif
If you want multiple enums in one file, you can do this (although you have to temporarily define public to be nothing for C / C++):
#if __LINE__
#define public
#else
namespace MyNamespace
{
#endif
public enum MyEnum { MyEnumValue1, MyEnumValue2 };
public enum MyEnum2 { MyEnum2Value1, MyEnum2Value2 };
public enum MyEnum3 { MyEnum3Value1, MyEnum3Value2 };
#if __LINE__
#undef public
#else
}
#endif
You can expose the C# library to COM and then import the type library into the unmanaged code - this way you will be able to use the enum defined in C# library in the unmanaged library.
Unmanaged C++ and C# live in two different worlds, so no there is no way to use the same enum, without changing the c++ DLL into a managed one.
And even then, you'd probably need the duplication in the managed C++ DLL.
A C++ enum is much like a list of constants, whereas a C# enum inherits the Enum class, and thus provides quite a few "tricks". So as you can see, they're very different.
If it doesn't matter whether the native C++ DLL is native or managed, I'd turn it into a managed one and wrap the native calls inside a managed C++ Layer.
That way you can have the enum duplication inside the C++ DLL, and also you can get rid of all the interop at the same time :-)
I've had the same problem in the past and solved it using preprocessor definitions.
In your unmanaged code, inside a header that can also be included by your managed wrapper, place your enumeration items into a #define.
Then, in your managed and unmanaged enumeration definitions, use the same #define for both usages.
The movement of the enumerations between the managed and unmanaged world looks slightly nasty (basically a cast is needed), but to your caller in the unmanaged world, it'll look and feel fine.
Good luck,