Compatibility with ECMAScript Private Fields proposal #16324

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1. DanielRosenwasser commented on Jun 7, 2017

   

   Daniel Rosenwasser (DanielRosenwasser)

   on Jun 7, 2017

   Last edited by DanielRosenwasser

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   I think the two features can coexist together. One is design-time privacy which I think by and large has been useful for TypeScript users. It's a "soft" privacy check and this approach has its merits like debugging, and allowing consumers to use your code until you've figured out how you want to surface your API. The emit for our accessibility is entirely erased, which leads to simpler emit, while adding explicit intent to consumers; and intent goes a very long way in programming.

   The other is runtime privacy. This mode of privacy currently can't be used on methods on the prototype, or on static fields (and I don't know if there is any concrete proposal that does so). In other words, the following doesn't work

   classs C {
     // doesn't work
     #foo() {
       // ...
     }
   
     // doesn't work
     static #bar = 10;
   }

   You can think of TypeScript's design-time privacy checks as compatible with both instance field placement proposals, where run-time private fields can only be design-time private:

   TypeScript modifier...	with public fields	with private fields
   No modifier	Entirely public	Private at run-time & design-time
   public	Entirely public	Incompatible
   protected	Design-time protected	Incompatible
   private	Design-time private	Private at run-time & design-time

   In general, it's a set of tradeoffs for you to choose from. I think I and the majority of our team feel that design-time privacy is good enough on the whole. If private fields proceed, then you'll be able to choose something that enforces runtime checks as well if it's what you need, but keep the tradeoffs in mind.
2. Daniel Rosenwasser (DanielRosenwasser)

   added

   QuestionAn issue which isn't directly actionable in codeAn issue which isn't directly actionable in code

   on Jun 7, 2017
3. dennis-johnson-dev commented on Jun 7, 2017

   

   Dennis Johnson (dennis-johnson-dev)

   on Jun 7, 2017

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   Thank you so much for the thoughtful reply! There's a lot of great insight here in using what suits our needs best and understanding the tradeoffs. I'll go ahead and close this issue.

   👍React with 👍1Reacted by Daniel Rosenwasser
4. Dennis Johnson (dennis-johnson-dev)

   closed this as completedon Jun 7, 2017
5. microsoft

   locked and limited conversation to collaborators on Jun 14, 2018