News for hackers. Stuff that matters.

A comment on The unexpected productivity boost of Rust. Parent comment

Re:The unexpected productivity boost of Rust by const_cast on Wednesday August 27, 2025 @10:27PM (#45047653)
C++ auto copies as well, it's just a feature of value semantics. References must be taken manually - versus Java or C#, where we assume reference and then have to explicitly say copy. Rust, I believe, usually moves by default - not copy, but close - for most types.

The nice thing about value semantics is they are very safe and can be very performant. Like in PHP, if we take array that's a copy. But not really - it's secretly COW under the hood. So it's actually very fast if we don't mutate, but we get the safety of value semantics anyway.

[ Parent | on HN ]
Re:The unexpected productivity boost of Rust by vlovich123 on Thursday August 28, 2025 @11:44AM (#45053644)
Rust will transparently copy values for types that declare the Copy trait. But the default is move which is probably what C++ would have chosen had they had the 30+ years of language research to experiment with that Rust did + some other language to observe what worked and what didn't.
[ Parent | on HN ]