# Rust Design Patterns

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


## Contents

[Introduction](intro.md)

### Idioms

* [Constructor](idioms/ctor.md)
* [Concatenating strings with `format!`](idioms/concat-format.md)
* [Privacy for extensibility](idioms/priv-extend.md)
* 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](idioms/deref.md)
* 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](idioms/dtor-finally.md)
* TODO interior mutability - UnsafeCell, Cell, RefCell
* [Iterating over an `Option`](idioms/option-iter.md)
* [`Default` trait](idioms/default.md)
* [Pass variables to closure](idioms/pass-var-to-closure.md)
* [`mem::replace(_)` to avoid needless clones](idioms/mem-replace.md)
* [Temporary mutability](idioms/temporary-mutability.md)
* TODO FFI usage (By being mindful of how to provide Rust libraries, and make use of existing libraries across the FFI, you can get more out of benefits Rust can bring)

### Design patterns

* [Builder](patterns/builder.md)
* [RAII guards](patterns/RAII.md)
* [Newtype](patterns/newtype.md)
* 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)
* TODO Module organisation (by looking at examples such as Rusts `libstd`, and how it integrated into the Rusts source code, lessons can be learned about ergonomic project management and API design. Closely assosciated with platform-specific sub-modules)
* [Entry API](patterns/entry.md) (TODO Currently just a boilerplate)
* [Visitor](patterns/visitor.md)
* [Fold](patterns/fold.md)
* [Prefer small crates](patterns/small-crates.md)
* [Contain unsafety in small modules](patterns/unsafe-mods.md)
* 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](patterns/late-bounds.md) (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](patterns/compose-structs.md)



### Anti-patterns

* TODO thread + catch_panic for exceptions
* TODO Clone to satisfy the borrow checker
* [Deref polymorphism](anti_patterns/deref.md)
* 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)]`](anti_patterns/deny-warnings.md)


## Contributing

Contributions are very welcome!

You should start with [the template](template.md). 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](https://github.com/rust-unofficial/patterns/issues)
so that other people don't start working on the same topic.

Correction and elaboration PRs are very welcome.