Typescript General Parameter Injection Decorator

general-parameter-injector.ts

function Inject(...args) {
    return (target, propertyKey?: string, descriptor?: PropertyDescriptor) => {
        if(propertyKey){
            var original_method:Function = descriptor.value;
            descriptor.value = function(...params){
                original_method.apply(target, params.concat(args));
            };
        }else{  
            // save a reference to the original constructor
            var original_method = target;
            // the new constructor behaviour
            var f : any = function (...params) {
                return  original_method.apply(this, params.concat(args));
            }
            // copy prototype so intanceof operator still works
            f.prototype = original_method.prototype;
            // return new constructor (will override original)
            return f;
        }
    };
}

//-------------------------------
//test
//-------------------------------

@Inject('name1')
class A{
    constructor(name, injected_name?) {
        console.log(name, injected_name);
    }

    @Inject('name2')
    print(name, injected_name?){
        console.log(name, injected_name);
        this.print2();
    }
    print2(){
        console.log('hehe');
    }
}
var ss = new A('ali');
ss.print('reza');

//-------------------------------
//output
//-------------------------------
ali name1
reza name2
hehe