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Provide a modifier to allow classes to protect property state while allowing mutations/changes within the class #39461
Description
Activity
If I understand correctly, you can already do it with private class fields: #30829, ECMAScript Private Fields on Handbook.
Right, you could write
class Dog { get asleep { return this.#asleep; } #asleep = true; wake() { this.#asleep = false; } }
and if you're okay with ordinary properties:
class Dog { get asleep { return this._asleep; } private _asleep = true; wake() { this._asleep = false; } }
Daniel Rosenwasser (@DanielRosenwasser) Jordi Oliveras Rovira (@j-oliveras) Thanks for the comment. I don't think you had addressed my use cases with your comment though, and I hope the 3 use cases below outlines them more clearly.
I have mentioned getters in my opening comment and think you misunderstand my intent as I do not want to use them at all. The use case as mentioned is to avoid extra code such as getters. You are using them in both your examples. It's small so you will only notice one line of code. But when you have a lot of properties securing ways to read my classes properties through getters becomes redundant. I have more lines of code to read through and the file becomes very large if newline characters with spacing between braces is a requirement in the lint.
The second use case is runtime. It's small, but you skip the work of one extra function call that will return the reference of the value you are trying to get through a getter. I know it's very very small, but this difference might mean something if there were lots of getters pointing to values needed to do math in an animation loop to keep at higher frame rates in a browser.
The third use case is file size. If Typescript had acted as my getters instead of me relying on javascript to be my getters to protect my properties from being modified externally, we can prevent:
get asleep { return this._asleep; }from being outputted at all.Javascript Output:
class Dog { constructor() { this._asleep = true; } wake() { this._asleep = false; } }
vs
class Dog { constructor() { this._asleep = true; } get asleep() { return this._asleep; } // ~ 40ish kb wake() { this._asleep = false; } }
This example is small, but on large projects, this really helps reduce characters with scale.
Search Terms
"modify readonly for internal classes" - leads to "as any" hack (Goal is to create convinience)
"protected" search - can only be read by derived classes
Suggestion
I find myself looking to complex solutions or longer code to protect state. I'm hoping typescript can be used to reduce code and protect state away from runtime through a public readonly modifier that has write access for internal methods of a class.
Use Cases
I'm hoping to save runtime through typing state protection and avoid extra code such as getters and frameworks that use runtime to manage state.
Examples
Checklist
My suggestion meets these guidelines: