Why don't we have variable getters and setters?

I have questions
1

I've been wondering why we don't have getters and setters to variables.
I get that it may be bad for performance and functions(or decorators) are better suited for this purpose.
so what's the reason??

2

This seems like something that would make code much harder to reason about and understand. What would be the use case?

1 Like
3

With property getters and setters it is clear to the reader who/what is responsible for handling the interaction.

thing.prop;

In the above code, we are asking thing for prop. In very very abstract terms this could be seen as thing being the receiver of a message with the information GET: prop. Languages like Smalltalk are modelled closed to this.

Compared to:

abc; // triggers a getter?

With a plain symbol acting as a getter it’s less clear (IMO) that there is a separate receiver that is involved in the interaction.

Also. variable getter/setters do exist in JS but only when in sloppy mode, using a proxy as the receiver for a with block. So it can be done but is unlikely to be the cleanest solution to the problem the code is trying to address.

1 Like
4

Note for completeness' sake: side effects on variable get/set are also possible by adding getters/setters to the global object (not that it's a good idea)

Object.defineProperty(window, 'foo', {
  get() { console.log('foo getter ran') },
  set(_) { console.log('foo setter ran') }
})
5

That only affects global variables. It's also possible to do the same with with.

Neither are patterns that I'd want to see encouraged or expanded.

1 Like
6

Yes here is related proposal in the Future extension part of the decorator proposal. https://www.github.com/tc39/proposal-decorators/tree/master/EXTENSIONS.md

7

let decorators are precisely what i needed!
They can help in reactivity, validation and much more. I would like to see them included in the language some day.