BoundMethods

Transparent method binding in TypeScript to persist the lexical scope of this. Usage: add the @bound decorator to methods.

class Foo {
    private foo = "hello, foo";

    @bound public bar() {
        console.log(this.foo);
    }
}

var foo = new Foo();

setTimeout(foo.bar, 500); // "hello, foo"

How it Works

Using @bound on an instance method will override the PropertyDescriptor of that method with a getter, that injects a bound version of the method into the instance object on the first invocation. Subsequent calls will use the method on the instance object, effectively hiding the original unbound method on the prototype object. The side-effect of this is that modifications to the prototype method will have no effect.

Using @bound on a static method will simply override it with a bound version on the constructor function itself.

What's the point

Arrow methods were introduced since I've made this decorator, which renders @bound somewhat obsolete when used on its own (because you could just simply use arrow methods instead).

However, if you also happen to be using other decorators on your class methods, @bound will help you bind your methods correctly without having to do it manually, e.g. in the constructor:

@bound
@retry
@throttle
public foo() {
    ...
}

When using @bound with other decorators, you'll often need to place it behind the others.

License

MIT, enjoy.