alt Hacker NewsOne example where Rust enables better and faster abstractions is traits. C you can do this with some ugly methods like macros and such but in Rust it’s not the implementers choice it’s the callers choice whether to use dynamic dispatch (function pointer table in C) or static dispatch (direct function calls!)
In c the caller isn’t choosing typically. The author of some library or api decides this for you.
This turns out to be fairly significant in something like an embedded context where function pointers kill icache and rob cycles jumping through hoops. Say you want to bit bang a bus protocol using GPIO, in C with function pointers this adds maybe non trivial overhead and your abstraction is no longer (never was) free. Traits let the caller decide to monomorphize that code and get effectively register reads and writes inlined while still having an abstract interface to GPIO. This is excellent!
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> In c the callers isn’t choosing typically. The author of some library or api decides this for you.
Tbf this applies to Rust too. If the author writes
fn foo(bar: Box<dyn BarTrait>)
Had they written
fn foo(bar: impl BarTrait)
It's a tradeoff though, as I think traits makes the Rust build times grow really quickly. I don't know the exact characteristics of it, also I think they speed it up compared to how it used to be, but I do remember that you'll get noticeable build slowdowns the more you use traits, especially "complicated" ones.
The C way is to avoid abstractions in first place.
I probably enjoy ELF hacking more than most, but patching an ELF binary via LD_PRELOAD, linker hacks, or even manual or assisted relinking tricks are just tools in the bag of performant C/C++ (and probably Rust too, but I don't get paid to make that fast). If you care about perf and for whatever reason are using someone else's code, you should be intimately familiar with your linker, binary format, ABI, and OS in addition to your hardware. It's all bytes in the end, and these abstractions are pliable with standard tooling.
I'd usually rather have a nice language-level interface for customizing implementation, but ELF and Linux scripting is typically good enough. Binary patching is in a much easier to use place these days with good free tooling and plenty of (admittedly exploit-oriented) tutorials to extrapolate from as examples.