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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
citrus
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Rust is more portable than C for pngquant/libimagequant
I learned about a couple of your interesting things. Citrus, looks really cool and I'm eager to try it out. (Why does the Github say it's "superseded by c2rust"? I'm with you that sometimes readable output is better than accurate output.) gifski looks like huge fun and I'm eager to understand its algorithms better. I didn't realize until I looked that it is also Rust.
What are some alternatives?
rust-typed-arena - The arena, a fast but limited type of allocator
min-sized-rust - 🦀 How to minimize Rust binary size 📦
slab - Slab allocator for Rust
trophy-case - 🏆 Collection of bugs uncovered by fuzzing Rust code
multi_mut - Methods on HashMap and BTreeMap for safely getting multiple mutable references to the contained values.
rust - Rust for the xtensa architecture. Built in targets for the ESP32 and ESP8266
stdx - The missing batteries of Rust
nomicon - The Dark Arts of Advanced and Unsafe Rust Programming
rust - Empowering everyone to build reliable and efficient software.
gifski - GIF encoder based on libimagequant (pngquant). Squeezes maximum possible quality from the awful GIF format.
BLAKE3 - the official Rust and C implementations of the BLAKE3 cryptographic hash function
ghost-cell - An implementation of Joshua Yanovski's Ghost Cell paper.