Programming .NET Components, 2nd Edition

Generics Implementation

On the surface C# generics look syntactically similar to C++ templates, but there are important differences in the way they are implemented and supported by the compiler. This has significant implications for how you use generics.

Compared to C++ templates, C# generics can provide enhanced safety but are also somewhat limited in capabilities. In some C++ compilers, until you use a template class with a specific type, the compiler does not even compile the template code. When you do specify a type, the compiler inserts the code inline, replacing every occurrence of the generic type parameter with the specified type. In addition, every time you use a specific type, the compiler inserts the type-specific code, regardless of whether you have already specified that type for the template class somewhere else in the application. It is up to the C++ linker to resolve this, and it is not always possible to do so. This may result in code bloating, increasing both the load time and the memory footprint.

In .NET 2.0, generics have native support in the IL and the CLR itself. When you compile generic C# server-side code, the compiler compiles it into IL, just like it would any other type. However, the IL only contains parameters or placeholders for the actual specific types. In addition, the metadata of the generic server contains generic information.

The client-side compiler uses that generic metadata to support type safety. When the client provides a specific type instead ...