Version Issues for Value Types Nested in Native Types (C++/CLI)

Consider a signed (strong name) assembly component used to build a client assembly. The component contains a value type that is used in the client as the type for a member of a native union, a class, or an array. If a future version of the component changes the size or layout of the value type, the client must be recompiled.

Create a keyfile with sn.exe (sn -k mykey.snk).

Example

The following sample is the component.

// nested_value_types.cpp
// compile with: /clr /LD
using namespace System::Reflection;
[assembly:AssemblyVersion("1.0.0.*"), 
assembly:AssemblyKeyFile("mykey.snk")];

public value struct S {
   int i;
   void Test() {
      System::Console::WriteLine("S.i = {0}", i);
   }
};

This sample is the client:

// nested_value_types_2.cpp
// compile with: /clr
#using <nested_value_types.dll>

struct S2 {
   S MyS1, MyS2;
};

int main() {
   S2 MyS2a, MyS2b;
   MyS2a.MyS1.i = 5;
   MyS2a.MyS2.i = 6;
   MyS2b.MyS1.i = 10;
   MyS2b.MyS2.i = 11;

   MyS2a.MyS1.Test();
   MyS2a.MyS2.Test();
   MyS2b.MyS1.Test();
   MyS2b.MyS2.Test();
}

Output

S.i = 5
S.i = 6
S.i = 10
S.i = 11

Comments

However, if you add another member to struct S in nested_value_types.cpp, (for example, double d;) and recompile the component without recompiling the client, the result is an unhandled exception (of type System.IO.FileLoadException).

See Also

Other Resources

Managed Types (C++/CLI)