slotmap
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slotmap | nomicon | |
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14 | 87 | |
1,031 | 1,685 | |
- | 3.4% | |
3.4 | 5.5 | |
about 2 months ago | 20 days ago | |
Rust | CSS | |
zlib License | Apache License 2.0 |
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For example, an activity of 9.0 indicates that a project is amongst the top 10% of the most actively developed projects that we are tracking.
slotmap
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Tree Borrows - A new aliasing model for Rust
It looks like .get_disjoint_mut() from slotmap failed under stacked borrows, but seems to pass under tree borrows
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Indexing vs Smart Pointers
I think slotmap is meant to solve this exact issue. Basically when you insert into a collection you get an Id:Version tuple as key. When you reuse a slot, next time the key will be Id:Version+1 and when you try to access the removed value by using Id:Version, it will return None. You can think about it as delayed invalidation.
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Hey Rustaceans! Got a question? Ask here (5/2023)!
Dunno about existing implementations, but it looks like it's a feature they'd accept: https://github.com/orlp/slotmap/issues/73
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Unsafe is a bad practice?
It's actually quite easy.
- Rust is more portable than C for pngquant/libimagequant
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Hey Rustaceans! Got an easy question? Ask here (50/2021)!
You can use either slot map or slab to side step rust borrow checker. Example https://github.com/orlp/slotmap/blob/master/examples/rand_meld_heap.rs
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Rust data structures with circular references
I don't know, only have some theories.
1. The name isn't particularly catchy or descriptive. It is the correct name for the data structure, but not too many people know the data structure.
2. People don't even know what they're missing. It's not a very Google-able problem to begin with. Slotmap provides an interesting solution to (circular) ownership and safe allocator / weak pointer design problems, but people don't recognize that they're having them or that slotmap could help.
As an example of this, the doubly linked list example (https://github.com/orlp/slotmap/blob/master/examples/doubly_...) can safely remove nodes from the linked list given their handle, in O(1), even from the middle, completely safely and correctly, even in the presence of double deletions or ABA memory re-use. You can't replicate this with just pointers, without introducing heavy refcounting solutions.
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Is it possible to write anything using 100% safe Rust?
Nope, it's perfectly safe: https://github.com/orlp/slotmap/blob/master/examples/doubly_linked_list.rs.
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Syncing HashMap values amongst User
I think keeping the relationship between child and parent elements in the node graph might be better accommodating better via a psuedo-ECS system, see https://www.reddit.com/r/rust/comments/cnjhup/idiomatic_way_to_reference_parent_struct/. The https://github.com/orlp/slotmap crate looks promising. I think I'm just going to ditch the global shared HashMap in favor of something that can better accommodate child/parent relations.
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Beginner question: does it become easier to write datastructures with complex ownership semantics?
I think the slotmap crate is similar to what you're trying to write: https://github.com/orlp/slotmap
nomicon
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[Media] I'm comparing writing a double-linked list in C++ vs with Rust. The Rust implementation looks substantially more complex. Is this a bad example? (URL in the caption)
itโs even written by the same person that wrote the Nomicon (the guide to the dark arts of unsafe)
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Rust books to read
If you want to dive deeper you can always have other options but now there are concrete cases, if you want to do low level thing https://doc.rust-lang.org/nomicon/ while if you want multi thread/concurrency stuff https://marabos.nl/atomics/ . There are many many books so you will have to point yourself to what you want
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Thread-shared boolean flag
Nonononono. SeqCst is the most error prone memory order: https://github.com/rust-lang/nomicon/issues/166
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[Media] Hashmap behaviour inside a loop due to lifetime issue
Hope this helps. For more details, see the Rustonomicon. I referenced the subtyping chapter here extensively.
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Unsafe Rust
Nice video! Glad I could help out. This stuff is hard, and I'm still learning a lot about it myself even years later. The Rustonomicon is a great read if you haven't already.
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Stepping up the YAML engineer game
Have you got a moment to read through the good book , after reading through this perhaps try the Rustonomicon.
- Questions about ownership rule
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CppCon 2022 Best Practices Every C++ Programmer Needs to Follow โ Oz Syed
That is not what UB means. Undefined Behaviour is behaviour that the compiler is allowed to assume will never happen, and which can consequently cause miscompilations due to optimisation passes gone wrong if it does in fact occur in the source code.
It's true that Rust does not have a written specification that clearly delineates what is and isn't UB in a single place. But:
1. UB is impossible in safe code (modulo bugs in unsafe code)
2. There are resources such as the Rustinomicon (https://doc.rust-lang.org/nomicon/) that provide a detailed guide on what is and isn't allowed in unsafe code.
In practice, it's much easier to avoid UB in Rust than it is in C++.
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How to write deserializer for custom binary protocol?
However, this is a wide topic out of scope for a Reddit comment, so maybe just read the Rustonomicon. It explains everything about data handling in Rust.
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Performance critical ML: How viable is Rust as an alternative to C++
The ownership model & borrow checker makes rust a bit of an awkward language in which to write complex data structures like trees and graphs. It can be done - since you can always use raw pointers & unsafe code when you absolutely need to to treat rust like C. But the language fights you, and the community can get a bit moralistic about this sort of thing. The rust nomicon is a fantastic resource for learning the limits of the borrow checker, and where and how to use unsafe code correctly. You will need unsafe less than you think you will, but sometimes you will have no choice.
What are some alternatives?
rust-typed-arena - The arena, a fast but limited type of allocator
book - The Rust Programming Language
slab - Slab allocator for Rust
mdBook - Create book from markdown files. Like Gitbook but implemented in Rust
multi_mut - Methods on HashMap and BTreeMap for safely getting multiple mutable references to the contained values.
rust-ffmpeg - Safe FFmpeg wrapper.
rust - Rust for the xtensa architecture. Built in targets for the ESP32 and ESP8266
Theseus - Theseus is a modern OS written from scratch in Rust that explores ๐ข๐ง๐ญ๐ซ๐๐ฅ๐ข๐ง๐ ๐ฎ๐๐ฅ ๐๐๐ฌ๐ข๐ ๐ง: closing the semantic gap between compiler and hardware by maximally leveraging the power of language safety and affine types. Theseus aims to shift OS responsibilities like resource management into the compiler.
stdx - The missing batteries of Rust
Exercism - website - The codebase for Exercism's website.
rust - Empowering everyone to build reliable and efficient software.
miri - An interpreter for Rust's mid-level intermediate representation