tgotwig / patterns

A catalogue of Rust design patterns

Rust Design Patterns

An open source repository of design patterns and idioms in the Rust programming language.

Contents

Introduction

Idioms

• Constructor
• Concatenating strings with format!
• Privacy for extensibility
• TODO stability for extensibility
• TODO trait to separate visibility of methods from visibility of data (https://github.com/sfackler/rust-postgres/blob/master/src/lib.rs#L1400)
• Collections are smart pointers
• TODO leak amplification ("Vec::drain sets the Vec's len to 0 prematurely so that mem::forgetting Drain "only" mem::forgets more stuff. instead of exposing uninitialized memory or having to update the len on every iteration")
• Finalisation in destructors
• TODO interior mutability - UnsafeCell, Cell, RefCell
• Iterating over an Option
• Default trait
• Pass variables to closure
• mem::replace(_) to avoid needless clones
• Temporary mutability

Design patterns

• Builder
• RAII guards
• Newtype
• TODO iterators (to safely avoid bounds checks)
• TODO closures and lifetimes (coupling to lifetime)
• TODO platform-specific sub-modules (https://github.com/rust-lang/rfcs/blob/master/text/0517-io-os-reform.md#platform-specific-opt-in)
• Entry API (Currently just a boilerplate)
• Visitor
• Fold
• Prefer small crates
• Contain unsafety in small modules
• TODO extension traits
• TODO destructor bombs (ensure linear typing dynamically, e.g., https://github.com/Munksgaard/session-types/commit/0f25ccb7c3bc9f65fa8eaf538233e8fe344a189a)
• TODO convertible to Foo trait for more generic generics (e.g., http://static.rust-lang.org/doc/master/std/fs/struct.File.html#method.open)
• Late bound bounds (Currently just a boilerplate)
• TODO 'shadow' borrowed version of struct - e.g., double buffering, Niko's parser generator
• TODO composition of structs to please the borrow checker
• TODO Error traits and Result forwarding
• TODO graphs
• Compose structs together for better borrowing

Anti-patterns

• TODO thread + catch_panic for exceptions
• TODO Clone to satisfy the borrow checker
• Deref polymorphism
• TODO Matching all fields of a struct (back compat)
• TODO wildcard matches
• TODO taking an enum rather than having multiple functions
• TODO unwrap()ing every Result instead of forwarding it
• #[deny(warnings)]

Contributing

Contributions are very welcome!

You should start with the template. Copy it into the appropriate directory, edit it, and submit a PR. You might not want every section, and you might want to add extra sections.

We suggest leaving a comment on the issue tracker so that other people don't start working on the same topic.

Correction and elaboration PRs are very welcome.