[![Current version][crate-badge]][crates-io]
[![Current documentation][doc-badge]][docs]
[![Build status][build-badge]][builds]

# Shaku

Shaku is a compile time dependency injection Rust library. See the [docs] for
more details, including a getting started guide.

## Guides
* [General getting started guide, with components (aka singletons)][component-guide]
* [Providers (aka transient)][provider-guide]
* [Submodules][submodules-guide]

## Example
```rust
use shaku::{module, Component, Interface, HasComponent};
use std::sync::Arc;

trait Logger: Interface {
    fn log(&self, content: &str);
}

trait DateLogger: Interface {
    fn log_date(&self);
}

#[derive(Component)]
#[shaku(interface = Logger)]
struct LoggerImpl;

impl Logger for LoggerImpl {
    fn log(&self, content: &str) {
        println!("{}", content);
    }
}

#[derive(Component)]
#[shaku(interface = DateLogger)]
struct DateLoggerImpl {
    #[shaku(inject)]
    logger: Arc<dyn Logger>,
    today: String,
    year: usize,
}

impl DateLogger for DateLoggerImpl {
    fn log_date(&self) {
        self.logger.log(&format!("Today is {}, {}", self.today, self.year));
    }
}

module! {
    MyModule {
        components = [LoggerImpl, DateLoggerImpl],
        providers = []
    }
}

fn main() {
    let module = MyModule::builder()
        .with_component_parameters::<DateLoggerImpl>(DateLoggerImplParameters {
            today: "Jan 26".to_string(),
            year: 2020
        })
        .build();

    let date_logger: &dyn DateLogger = module.resolve_ref();
    date_logger.log_date();
}
```

## Component vs Provider
`Component` represents a single instance of a service, aka a singleton.
`Provider` is more like a factory for instances. Each time a component is
resolved you will get the same instance. Each time a provider is resolved you
will get a new instance.

For more details on `Component` and `Provider`, see the
[getting started guide][component-guide] and the
[provider getting started guide][provider-guide].

## Minimum Supported Rust Version
Shaku supports the latest stable release of Rust, plus the previous two versions
at minimum (but possibly more). Changes to the minimum supported version will be
noted in the changelog.

Minimum supported version: 1.38.0

## Project Status
The foundation of shaku's API is in place, and now the focus is to mature the
project based on user feedback. I ([@AzureMarker]) am active in the project, but
I do not have many major changes of my own planned for the future. Most of the
future changes will be based on user feedback.

## Acknowledgements
This library started off as "he_di" (later renamed to "shaku") under the
guidance of [@bgbahoue] and [@U007D]. Their work inspired the current maintainer
([@AzureMarker]) to continue the library from where they left off.

[crates-io]: https://crates.io/crates/shaku
[docs]: https://docs.rs/shaku
[builds]: https://circleci.com/gh/AzureMarker/shaku
[crate-badge]: https://img.shields.io/crates/v/shaku.svg
[doc-badge]: https://docs.rs/shaku/badge.svg
[build-badge]: https://circleci.com/gh/AzureMarker/shaku.svg?style=shield
[component-guide]: https://docs.rs/shaku/*/shaku/guide/index.html
[provider-guide]: https://docs.rs/shaku/*/shaku/guide/provider/index.html
[submodules-guide]: https://docs.rs/shaku/*/shaku/guide/submodules/index.html
[@bgbahoue]: https://github.com/bgbahoue
[@U007D]: https://github.com/U007D
[@AzureMarker]: https://github.com/AzureMarker