Suggestion Backlog Slog, 4/24/2017

[RyanCavanaugh]

• Allow interfaces to declare protected members and allow implementors to implement protected and private members. #3854 protected in interfaces
• Proposal: Support spread operator for arrays and tuples in function calls #5296 Spread for function calls
• unknown: less-permissive alternative to any #10715 unknown alternative to any
• Allow to call getter/setter logic When subclassing #338 Allow super.get/set
• Suggestion: Allow declaring class members within a constructor #766 Allow declaring class members in the constructor
• Should unions and non-primitives be allowed for relational comparisons? #5156 > operator and friends on union types
• Inherited typing for class property initializers #10570 Inherited typing for class property initializers
• Cannot Optionalize Class Getters #14417 Optional getters in classes
• Suggestions for misspelled properties and variables (based on Levenshtein distance for variables/properties in scope) #15333 Suggest closely-named identifiers
• NaN, Infinity and -Infinity not accepted in number literal types #15135 NaN/Infinity/-Infinity numeric literals
• Suggestion: one-sided or fine-grained type guards #15048 Non-exhaustive type guards

[RyanCavanaugh]

• Allow to call getter/setter logic When subclassing #338 Allow super.get/set
  • 👎 not enough demand, too complex of code to gen, and can't be statically checked for correctness
• Suggestion: Allow declaring class members within a constructor #766 Allow declaring class members in the constructor
  • Field initializers are coming
  • Quick fixes are here
  • 👎
• Should unions and non-primitives be allowed for relational comparisons? #5156 > operator and friends on union types
  • Turns out this was fixed
  • 👍
• Inherited typing for class property initializers #10570 Inherited typing for class property initializers
  • We gotta do something
  • Also affects string literals from the base type
  • Why not copy down the type blindly?
    • Back-compat break

      class Animal {
	me = new Animal();
	move() { }
}
class Dog extends Animal {
	me = new Dog();
	woof() {
		this.me.woof(); // Should be OK
    }
}

* Who should we break?
  * Ryan is happy to break contravariant writes
* Investigate more

• Cannot Optionalize Class Getters #14417 Optional getters in classes
  • Why?
    • Why did we allow it for methods?
    • It was a bug (?)
  • Is there a way to make the desired snippet compile?
    • No
    • Are we OK with that?
    • ... it's weird, in both directions
  • Why do you want to do this?
  • Accepting PRs if this wasn't just an idle curiousity
• Suggestions for misspelled properties and variables (based on Levenshtein distance for variables/properties in scope) #15333 Suggest closely-named identifiers
  • 👍 with a quickfix
  • Assign to Nathan so he can pick the best algorithm
• NaN, Infinity and -Infinity not accepted in number literal types #15135 NaN/Infinity/-Infinity numeric literals
  • These are not unit values (there are "more than one" NaN, Infinity, etc)
  • What is even for?
    • Who would write Math.sign(NaN) ?
  • 👎 Too Complex / scenarios not well-defined
• Suggestion: one-sided or fine-grained type guards #15048 Non-exhaustive type guards
  • More user-side complexity than compiler-side
  • isNumber(x): x extends number ?
  • May be hard to explain which to use
    • But you already have to understand this to decide if x is T is OK or not
  • AMF, gather more use cases