# coi
[](https://travis-ci.org/Nashenas88/coi)
[](https://docs.rs/coi)
[](https://crates.io/crates/coi)
Dependency Injection in Rust
The goal of this crate is to provide a simple dependency injection framework
that is easy to use. Performance is not an initial concern, but might be later
on as the crate matures.
### Example
```rust
use coi::{container, Inject};
use std::sync::Arc;
// Inherit `Inject` on all traits you'd like to inject
pub trait Trait1: Inject {
fn describe(&self) -> &'static str;
}
// derive `Inject` on all structs that will provide the implementation
#[derive(Inject)]
#[coi(provides dyn Trait1 with Impl1)]
struct Impl1;
// actually impl the trait
impl Trait1 for Impl1 {
fn describe(&self) -> &'static str {
"I'm impl1!"
}
}
pub trait Trait2: Inject {
fn deep_describe(&self) -> String;
}
#[derive(Inject)]
#[coi(provides dyn Trait2 with Impl2::new(trait1))]
struct Impl2 {
// inject dependencies by Arc<dyn SomeTrait>
#[coi(inject)]
trait1: Arc<dyn Trait1>,
}
impl Impl2 {
fn new(trait1: Arc<dyn Trait1>) -> Self {
Self { trait1 }
}
}
impl Trait2 for Impl2 {
fn deep_describe(&self) -> String {
format!("I'm impl2! and I have {}", self.trait1.describe())
}
}
// It even works on structs
#[derive(Debug, Inject)]
#[coi(provides JustAStruct with JustAStruct)]
pub struct JustAStruct;
fn main() {
// Then construct your container with the helper `container!` macro
let container = container!{
trait1 => Impl1Provider,
trait2 => Impl2Provider; scoped,
struct => JustAStructProvider; singleton
};
// And resolve away!
let trait2 = container
.resolve::<dyn Trait2>("trait2")
.expect("Should exist");
println!("Deep description: {}", trait2.as_ref().deep_describe());
let a_struct = container
.resolve::<JustAStruct>("struct")
.expect("Should exist");
println!("Got struct! {:?}", a_struct);
}
```
#### Name
The name coi comes from an inversion of the initialism IoC (Inversion of
Control).
#### License
<sup>
Licensed under either of <a href="LICENSE.Apache-2.0">Apache License, Version
2.0</a> or <a href="LICENSE.MIT">MIT license</a> at your option.
</sup>
<br/>
<sub>
Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in this crate by you, as defined in the Apache-2.0 license, shall
be dual licensed as above, without any additional terms or conditions.
</sub>
`SPDX-License-Identifier: MIT OR Apache-2.0`