nject 0.2.2

# nject ![Rust](https://github.com/nicolascotton/nject/workflows/Rust/badge.svg)

Simple zero cost dependency injection library made for rust
## Install

Add the following to your `Cargo.toml`:
```toml
[dependencies]
nject = "0.2"
```
## Use cases

### Removes the need to specify dependencies across your modules

```rust
use nject::{injectable, provider};

#[injectable]

struct DepOne;

#[injectable]

struct DepTwo {
    dep: DepOne,
}

#[injectable]

struct Facade {
    dep: DepTwo,
}

#[provider]

struct Provider;

fn main() {
    let _facade: Facade = Provider.provide();
}

```
### Works with lifetimes - enables shared dependencies

```rust
use nject::{injectable, provide, provider};

#[injectable]

struct DepOne;

#[injectable]

struct Facade<'a> {
    dep: &'a DepOne,
}

#[provider]

#[provide(&'a DepOne, self.shared)]

struct Provider<'a> {
    shared: &'a DepOne,
}

fn main() {
    let provider = Provider { shared: &DepOne };
    let _facade: Facade = provider.provide();
}

```
### Works with dyn traits

```rust
use nject::{injectable, provide, provider};

trait Greeter {
    fn greet(&self);
}

#[injectable]

struct GreeterOne;

impl Greeter for GreeterOne {
    fn greet(&self) {
        println!("Greeting");
    }
}

#[injectable]

struct Facade<'a> {
    boxed_dep: Box<dyn Greeter>,
    ref_dep: &'a dyn Greeter,
}

#[provider]

#[provide(Box<dyn Greeter>, Box::<GreeterOne>::new(self.provide()))]

#[provide(&'prov dyn Greeter, &self.greeter)]

struct Provider {
    greeter: GreeterOne,
}

fn main() {
    let provider = Provider { greeter: GreeterOne };
    let _facade: Facade = provider.provide();
}

```
### Works with generics

```rust
use nject::{injectable, provider};

#[injectable]

struct DepOne;

#[injectable]

struct Facade<T> {
    dep: T,
}

#[provider]

struct Provider;

fn main() {
    let _facade: Facade<DepOne> = Provider.provide();
}

```
### Works with generic providers

```rust
use nject::{injectable, provide, provider};

trait Greeter {
    fn greet(&self);
}

#[injectable]

struct DevGreeter;

impl Greeter for DevGreeter {
    fn greet(&self) {
        println!("Greeting Dev");
    }
}

#[injectable]

struct ProdGreeter;

impl Greeter for ProdGreeter {
    fn greet(&self) {
        println!("Greeting production");
    }
}

#[injectable]

struct Facade<'a> {
    dep: &'a dyn Greeter,
}

#[provider]

#[provide(&'a dyn Greeter, self.0)]

struct Provider<'a, T: Greeter>(&'a T);

fn main() {
    let _dev_facade: Facade = Provider(&DevGreeter).provide();
    let _prod_facade: Facade = Provider(&ProdGreeter).provide();
}
```
### Easily inject non-injectable dependencies

```rust
use nject::{inject, injectable, provide, provider};

#[inject(Self { non_injectable_value: 123 })]

struct InjectableFromInjectAttr {
    non_injectable_value: i32,
}

struct NonInjectable {
    non_injectable_value: i32,
}

#[inject(Self { non_injectable_value: injectable_dep.non_injectable_value + 10, injectable_dep }, injectable_dep: InjectableFromInjectAttr)]

struct PartiallyInjectable {
    non_injectable_value: i32,
    injectable_dep: InjectableFromInjectAttr
}

#[injectable]

struct Facade {
    dep_from_injected: InjectableFromInjectAttr,
    dep_from_partial_inject: PartiallyInjectable,
    #[inject(NonInjectable { non_injectable_value: 456 })]
    dep_from_inject_attr: NonInjectable,
    #[inject(InjectableFromInjectAttr { non_injectable_value: 789 })]
    dep_from_inject_attr_override: InjectableFromInjectAttr,
    #[inject(PartiallyInjectable { non_injectable_value: 111, injectable_dep }, injectable_dep: InjectableFromInjectAttr)]
    dep_from_partial_inject_attr_override: PartiallyInjectable,
}

#[provider]

struct Provider;

fn main() {
    let _facade = Provider.provide::<Facade>();
}
```
## Examples

You can look into the [axum](https://github.com/nicolascotton/nject/tree/main/examples/axum) example for a web API use case.
## Credits

- [Syn](https://github.com/dtolnay/syn) - [MIT](https://github.com/dtolnay/syn/blob/master/LICENSE-MIT) or [Apache-2.0](https://github.com/dtolnay/syn/blob/master/LICENSE-APACHE)
- [Quasi-Quoting](https://github.com/dtolnay/quote) - [MIT](https://github.com/dtolnay/quote/blob/master/LICENSE-MIT) or [Apache-2.0](https://github.com/dtolnay/quote/blob/master/LICENSE-APACHE)
- [Rust](https://github.com/rust-lang/rust) - [MIT](https://github.com/rust-lang/rust/blob/master/LICENSE-MIT) or [Apache-2.0](https://github.com/rust-lang/rust/blob/master/LICENSE-APACHE)