c# - Placing custom code in a System namespace

Question

Are there any best-practices that state custom code shouldn't be placed in a System namespace? Should System and its children be reserved for Microsoft code?

I ask because I'm writing a class library that will be used across many projects and I'd like to keep things consistent by placing it in System.InteropServices (since it deals with P/Invoke).

Answer 1

It's not a good idea because it defeats one of the primary benefits of namespaces: preventing name clashes. What if a newer version of the framework introduced an identically named type in that namespace?

This is particularly bad for System namespaces since they are imported in many other pieces of code with using directives and introducing custom types in those namespaces pollutes the naming scope of other source files with unexpected identifiers.

To categorize your custom interop related types, you can create a new namespace like MyProduct.InteropServices.