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Comment by andy_xor_andrew | Hacker News Reader

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.

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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

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.

I wrote 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.

macros can help with this if you can narrow down the traits you want to support.

https://doc.rust-lang.org/reference/macros.html

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

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).

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.

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