TypeScript decorators introduction test

decorators.ts

// src.: http://blog.wolksoftware.com/decorators-reflection-javascript-typescript
// run: ts-node decorators.ts

function log(target: any, key: string, value: any) {
  return {
    value(...args: any[]) {
      let a = args.map(a => JSON.stringify(a)).join()
      let result = value.value.apply(this, args)
      let r = JSON.stringify(result)
      console.log(`Call: ${key}(${a}) => ${r}`)
      return result
    }
  }
}

class C {
  @log
  foo(n: number) {
    return n * 2
  }
}

new C().foo(5)