3 ms·

One of the biggest struggles I have (and others have, judging from Stack Overflow) is how to generically handle accepting types of Box<T>, Rc<T>, T, Pin<T>, &T,

One of the biggest struggles I have (and others have, judging from Stack Overflow) is how to generically handle accepting types of Box<T>, Rc<T>, T, Pin<T>, &T, &mut T, etc etc. Of course you can write a function that is generic on <I, T: AsRef<I>> or something, but the moment you introduce function-coloring stuff like async, object safety, etc, things explode.

pylua 2y ago
Is that by design ? I am a novice at rust, but that is sort of how it feels. I could be missing something.
- pornel 2y ago
  It requires supporting higher-kinded types, and Rust was reluctant to add them (although it’s slowly getting there with higher kinded lifetimes and generic associated types).
unstruktured 2y ago
macros can help with this if you can narrow down the traits you want to support. https://doc.rust-lang.org/reference/macros.html https://doc.rust-lang.org/reference/macros.html
3836293648 2y ago
You just write an &T version and let everyone coerce their smart pointer into a reference on call? Worst case you write your generic asref function and then immediately delegate to the &T version
- deleted 2y ago
  [deleted]
vishalontheline 2y ago
Is there an ELI5 video / tutorial for all things box-variables that you can recommend? I understand pointers, I understand references, I understand ownership and mutability. I feel lost with Box things. The official documentation came across as cryptic to me and I had a hard time getting over the syntax. Like, what is "T" and why does it get passed into Box<> ... etc.
mmastrac 2y ago
I wrote https://github.com/mmastrac/keepcalm https://github.com/mmastrac/keepcalm as a way to help with this, especially for writing webserver-like code. For most cases this type of code can take a small perf hit in exchange for drastically simplifying the sharing of data in the system.
wtetzner 2y ago
Yeah, I typically use `impl AsRef<T>`. It would be really nice to be able to say roughly the same thing, but have the `.as_ref()` call happen at the call site instead of within the function.

pylua 2y ago

Is that by design ? I am a novice at rust, but that is sort of how it feels. I could be missing something.

pornel 2y ago
It requires supporting higher-kinded types, and Rust was reluctant to add them (although it’s slowly getting there with higher kinded lifetimes and generic associated types).

unstruktured 2y ago

macros can help with this if you can narrow down the traits you want to support. https://doc.rust-lang.org/reference/macros.html https://doc.rust-lang.org/reference/macros.html

3836293648 2y ago

You just write an &T version and let everyone coerce their smart pointer into a reference on call? Worst case you write your generic asref function and then immediately delegate to the &T version

deleted 2y ago
[deleted]

vishalontheline 2y ago

Is there an ELI5 video / tutorial for all things box-variables that you can recommend? I understand pointers, I understand references, I understand ownership and mutability. I feel lost with Box things. The official documentation came across as cryptic to me and I had a hard time getting over the syntax. Like, what is "T" and why does it get passed into Box<> ... etc.

mmastrac 2y ago

I wrote https://github.com/mmastrac/keepcalm https://github.com/mmastrac/keepcalm as a way to help with this, especially for writing webserver-like code. For most cases this type of code can take a small perf hit in exchange for drastically simplifying the sharing of data in the system.

wtetzner 2y ago

Yeah, I typically use `impl AsRef<T>`. It would be really nice to be able to say roughly the same thing, but have the `.as_ref()` call happen at the call site instead of within the function.