I flipped through one of my Rust projects and the best use case I saw was for serializing messages for disk / network / IPC: // This derive macro expands t

I flipped through one of my Rust projects and the best use case I saw was for serializing messages for disk / network / IPC: // This derive macro expands to a visitor pattern during build #[derive (serde::Serialize)] enum Message { QueryFoo (QueryFoo), MutateBar (MutateBar), } struct QueryFoo { foo_id: i64, } // If we receive a Message::MutateBar from outside our process, // it's a compile error for us to accidentally access the field `QueryFoo::foo_id`. struct MutateBar { bar_id: String, baz_value: u32, } fn send_msg_as_json (tx: &mut Sender, msg: &Message) -> anyhow::Result <()> { // The JSON serialization / deserialization is generated, too tx.send (serde_json::to_string (msg))?; Ok (()) } It's possible to represent this in C++, and you can integrate FlatBuffers or whatever to auto-generate the ser/de code, but then you're not writing C++, you're writing some weird DSL and you're fighting the build system and you're teaching juniors how to install it. I haven't seen anything in C++ that's both as easy and as airtight as a Rust enum with serde's automatic serialization macro on the top.