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Syrette
The convenient dependency injection & inversion of control framework for Rust.
Namesake
From the syrette Wikipedia article.
A syrette is a device for injecting liquid through a needle. It is similar to a syringe except that it has a closed flexible tube (like that typically used for toothpaste) instead of a rigid tube and piston.
Features
- A dependency injection and inversion of control container
- Autowiring dependencies
- API inspired from the one of InversifyJS
- Helpful error messages
- Supports generic implementations & generic interface traits
- Binding singletons
- Injection of third-party structs & traits
- Named bindings
- Async factories
Optional features
factory. Binding factories (Rust nightly required)prevent-circular. Detection and prevention of circular dependencies. (Enabled by default)async. Asynchronous support
To use these features, you must enable it in Cargo.
Why inversion of control & dependency injection?
The reason for practing IoC and DI is to write modular & loosely coupled applications.
This is what we're trying to avoid:
impl Foo
{
/// ❌ Bad. Foo knows the construction details of Bar.
pub fn new() -> Self
{
Self {
bar: Bar::new()
}
}
The following is better:
impl Foo
/// ✅ Better. Foo is unaware of how Bar is constructed.
pub fn new(bar: Bar) -> Self
{
Self {
bar
}
}
}
This will however grow quite tiresome sooner or later when you have a large codebase with many dependencies and dependencies of those and so on. Because you will have to specify the dependencies someplace
let foobar = Foobar::new(
Foo:new(
Woof::new(),
Meow::new()),
Bar::new(
Something::new(),
SomethingElse::new(),
SomethingMore::new()
)
)
This is where Syrette comes in.
Motivation
Other DI & IoC libraries for Rust are either unmaintained (di for example), overcomplicated and requires Rust nightly for all functionality (anthill-di for example) or has a weird API (teloc for example).
The goal of Syrette is to be a simple, useful, convenient and familiar DI & IoC library.
Example usage
use std::error::Error;
use syrette::injectable;
use syrette::DIContainer;
use syrette::ptr::TransientPtr;
trait IWeapon
{
fn deal_damage(&self, damage: i32);
}
struct Sword {}
#[injectable(IWeapon)]
impl Sword
{
fn new() -> Self
{
Self {}
}
}
impl IWeapon for Sword
{
fn deal_damage(&self, damage: i32)
{
println!("Sword dealt {} damage!", damage);
}
}
trait IWarrior
{
fn fight(&self);
}
struct Warrior
{
weapon: TransientPtr<dyn IWeapon>,
}
#[injectable(IWarrior)]
impl Warrior
{
fn new(weapon: TransientPtr<dyn IWeapon>) -> Self
{
Self { weapon }
}
}
impl IWarrior for Warrior
{
fn fight(&self)
{
self.weapon.deal_damage(30);
}
}
fn main() -> Result<(), Box<dyn Error>>
{
let mut di_container = DIContainer::new();
di_container.bind::<dyn IWeapon>().to::<Sword>()?;
di_container.bind::<dyn IWarrior>().to::<Warrior>()?;
let warrior = di_container.get::<dyn IWarrior>()?.transient()?;
warrior.fight();
println!("Warrior has fighted");
Ok(())
}
For more examples see the examples folder.
Terminology
Transient
A type or trait that is unique to owner.
Singleton
A type that only has a single instance. The opposite of transient. Generally discouraged.
Interface
A type or trait that represents a type (itself in the case of it being a type).
Factory
A function that creates new instances of a specific type or trait.
Default factory
A function that takes no arguments that creates new instances of a specific type or trait.
Rust version requirements
Syrette requires Rust >= 1.62.1 to work. This is mainly due to the dependency on Linkme.
Todo
- Add support for generic factories
Contributing
You can reach out by joining the mailing list.
This is the place to submit patches, feature requests and to report bugs.