A tiny dependency injection library for Rust.

This library provides a simple way to inject dependencies into structs. Injectiny is not a framework, but can be used inside one. Please refer to the README.md for an example of how to use it.

Installation

To use Injectiny, make sure to include both the injectiny and injectiny_proc_macro crates.

cargo add injectiny
cargo add injectiny_proc_macro

Example

use std::cell::RefCell;
use std::rc::Rc;
use injectiny::{Injected, Injectable};
use injectiny_proc_macro::injectable;

// Model is an enum defining all the fields that can be injected
#[derive(Clone)]
enum Model {
   Name(Rc<RefCell<String>>),   // non-clonable objects should be wrapped in Rc<RefCell<T>>
   Age(u32)
}

// The #[injectable] attribute macro generates an implementation of the Injectable trait for
// the given Model enum. In real situations, this could be one of several controllers, views, ...
#[injectable(Model)]
#[derive(Default)]
struct Injectee
{
    // The #[inject] attribute macro marks a field as injectable with the enum member. The field
    // type must be Injected<T>, where T is the type of the enum member's value.
    #[inject(Model::Name)]
    name: Injected<Rc<RefCell<String>>>,

    #[inject(Model::Age)]
    age: Injected<u32>
}

// This would represent a model
let name = Rc::new(RefCell::new("Patje".to_string()));
let age = 25;

// This could be one of many views
let mut injectee: Injectee = Default::default();
injectee.inject(Model::Name(name));
injectee.inject(Model::Age(age));

// The injected fields can be accessed like normal references
assert_eq!(&*injectee.name.borrow(), "Patje");
assert_eq!(*injectee.age, 25);