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();