decorators_and_annotations_part_1.1.ts

function log<T>(target: T, key :string, descriptor :any): T {
	var originalMethod = descriptor.value;

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

	return descriptor;
}

class Coffee {
	protected cost :number = 1.2;

	@log getCost() :number { return this.cost }

	@log someDo() { return 'some text' }
}

let myCoffee = new Coffee;
let cost = myCoffee.getCost();
myCoffee.someDo();

/*
Output:

Call: getCost() => 1.2
Call: someDo() => "some text"
*/