Revive restricted with() statement

πŸ’‘ Ideas
1

The with statement is not available at all in strict mode, because it leads to ambiguity and has other problems. However, would it be possible and sensible to reintroduce a subset of its functionality, e.g. limiting the parenthetical expression to predefined objects like Math?

var a, x, y;
var r = 10;

with (Math) {
  a = PI * r * r;
  x = r * cos(PI);
  y = r * sin(PI / 2);
}

(Example courtesy of MDN.)

var a, x, y;
var r = 10;
const Ο€ = Math.PI;

a = Ο€ * r * r;
x = r * Math.cos(Ο€);
y = r * Math.sin(Ο€ / 2);

var a, x, y;
var r = 10;

a = Math.PI * r * r;
x = r * Math.cos(Math.PI);
y = r * Math.sin(Math.PI / 2);
2

All predefined objects are mutable; you can add your own properties to Math, for example (not that it’s a good idea) - so that wouldn’t be any different than allowing it for normal objects.

1 Like
3

I think this is unlikely to happen, with is hated by a bunch of the committee. Additionally, I don't find with (Math) { … } to be any better than const { … } = Math for getting easy (and understandable) references to properties.

1 Like