Adds ability to optionalize class getters

[bradenhs]

Fixes #14417

This PR makes it to possible to optionalize class getters in the same way class methods can be marked optional:

class Person {
    firstName: string;
    lastName: string;

    get fullName?() {
        return this.firstName + " " + this.lastName;
    }
}

const me: Person = {
    firstName: "foo",
    lastName: "bar"
}

The above code should now work whereas before there was a syntax error. This is my first TypeScript PR so I hope I covered everything. This PR should handle:

• Updating the declaration emit
• Ensuring strictNullChecks works as expected with optional class getters
• Ability to omit optional class getter body

Hopefully I didn't miss anything, but I am of course more than happy to fix any issues.

[DanielRosenwasser]

Hey @bradenhs thanks for the PR! One thing that I'd like to ask is whether you could break your tests into multiple files. It seems like there's a lot of stuff you're trying to test (including intentional syntax errors), so I think it'd be a good idea to break that into multiple granular tests.

[bradenhs]

No problem. I'm traveling now but should have some time within the next week or so to make that change. I would love any other feedback in the meantime.

[Dashue]

Would love to see this functionality as well, any updates?

[bradenhs]

Started first post-college job this summer. Don't have as much coding free time as I once had :) But I have plans to get back to this again before the year is out.

[jeanpfs]

Any updates?

[mhegazy]

@Andy-MS and @weswigham can you please review

[bradenhs]

So I've been putting off crossing the finish line with this for a while but would definitely love any additional reviews! It might give me the motivation to finish this up.

[ghost]

Why only get? Seems like set should be allowed to be optional as well.

[bradenhs]

So bear with me as I try to remember my thinking on this. I believe there are two reasonable choices for how to implement this:

1. Whenever get is optional set must be marked optional as well. set cannot be marked optional if get is not marked optional.
2. Only allow marking get as optional. set can never be marked optional.

I went with the second of those choices because marking set as optional seemed weird. I wasn't sure what set someProperty?(value) { ... really communicates. The only advantage of option 1 in my eyes is that if someone sees that set is optional they'll know for sure that the corresponding get is optional as well. To be honest, I don't have a strong opinion on this either way.

[ghost]

If I understand the PR correctly, its effect is that when a class is used as an interface, the implementer doesn't have to provide a getter. So, what if you have:

class C {
    get x?() { return 0; }
    set x(value: number) { ... }
}
const impl: C = { }; // Should error?

Shouldn't I need both the getter and setter to be optional for compilation to succeed? After all, the following is a compile error today:

class C {
    set x(value: number) { }
}
const impl: C = {}; // Error, needs a setter for 'x'

[bradenhs]

FYI: I probably won't get to this within the next couple weeks. I still want to finish it up but it'll be slow going.

[bradenhs]

To anyone who wants to take this PR over feel free to do so. I'd still like to finish it up but evidently it's not a priority because I'm not making time for it :) I may get to it eventually but don't want to keep someone else from tackling this if they're interested!

[RyanCavanaugh]

@bradenhs thanks for the work so far! Will let someone else pick this up if they're able to.

[ericcarino]

Thanks for the work @bradenhs . It sucks that no one has the time to finish this off (like myself). This feature would have come in handy for me.

[bigzoo]

@RyanCavanaugh could you put down what needs to be added to get this work completed? Willing to take it up

[dapug]

How can this possibly have been abandoned? Seems absolutely fundamental, essential. What is the work-around?

[artem-v-shamsutdinov]

Here is what I did to get around this:
class Example {

constructor() {
delete this.val
Object.defineProperty(this, 'val', {
get() {
return whatever
},
set(
val: string
) {
// do whatever
}
});
}

val?: string
}

[DougSPol]

Ping - too bad this wasn't merged, super want this ability

[abhinandan-chakraborty]

when will this get solved?

[pishangujeniya]

Don't know why this was not prioritized. 😞

[MnariMohamed]

2024 and this is still not fixed