Code Generation in Rust vs C++26
Code Generation in Rust vs C++26
One of the things I like to do is compare how different languages solve the same problem — especially when they end up having very different approaches. It’s always educational. In this case, a bunch of us have been working hard on trying to get reflection — a really transformative language feature ...
This is a blog post that really is about C++, but with a look at how Rust does things. So, this is an interesting C++/Rust comparison for once.
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In Rust, you provide a string — that is injected to be invoked internally. In C++, we’d just provide a callable.
This is because Rust’s attribute grammar can’t support a callable here.
I don't do C++ as a life choice, and thus not 100% sure what the author means here. But I have the feeling that he is wrong, on multiple levels even 😉
Correct - Rust's attribute grammar allows any parseable sequence of tokens enclosed in
#[attr ...]basically. Serde specifically requires things to be in strings, but this is not a requirement of modern Rust or modern versions ofsyn(if you're comfortable writing your own parser for the meta).The author is not a Rust expert though, so I'm not surprised to see this assumption. It doesn't take away from the article though.
Edit: for fun,
synhas an example parsing an attribute in an attributeNot only that. We don't just "inject" raw strings with the
syn/quoteduality. Stringified or not, the token tree will be parse-checked into the expectedsyntype before being used in generated code.So the distinction is both wrong and irrelevant. This is what I meant by wrong on multiple levels/layers 😉