@anzerr/inject.ts

Intro

A simple example of a decorator for dependency injection.

Install

npm install --save git+https://github.com/anzerr/inject.ts.git
npm install --save @anzerr/inject.ts

Example

import 'reflect-metadata';
import {Injectable, Inject, Module} from 'inject.ts';

@Injectable()
class Config {

    constructor() {}

    get() {
        return {
            start: Math.floor(Math.random() * 10)
        };
    }

}

@Injectable()
class Log {
    count: number;

    constructor(@Inject(Config) config: Config) {
        this.count = config.get().start;
    }

    info(...arg) {
        this.count += 1;
        return console.log(this.count, ...arg);
    }

}

class Ping {
    @Inject(Log)
    logger: Log;

    interval: any;

    constructor() {
        this.interval = setInterval(() => this.logger.info('ping'), 5000);
    }

    close() {
        clearInterval(this.interval);
    }

}

new Module([Ping]).build();

Circular Dependency

Best to have zero but you can make them work if you need them after class construction

class A {

    @Inject(B) // 2. start to init "B"
    b: B; // 4. "B" finished construction injected into "A"

    constructor() { // 1. init "A" (added to instance list)
        // don't need "B" now but later in the class usage
    }

}

class B {

    a: A;

    constructor(@Inject(A) a) { // 3. look up "A" (found in instance list)
        // need "A" here
        this.a = a;
    }

}

new Module([A]).build();