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Design Meeting Notes, 9/13/2019 #33422
Description
Private Fields in .d.ts Files
- One issue is that
.d.tsfiles are sometimes lossy becauseprivatefields omit their types.- We probe the structure
- The variance issue sounds like something we're not likely to address.
- It's broken today for
private, why change for#?
- It's broken today for
- Perhaps it makes sense to just include a single
#_declaration in the output if we're just erasing all details.- Why don't we just include the original privates in the class declarations?
- Because you don't want 30 privates in your classes?
- But that's the case for
privateproperties today.
- Do private fields affect incremental and project references?
- Yes, but they probably shouldn't.
- A point in favor of emitting a single private property?
- Why don't we just include the original privates in the class declarations?
- So
#_?#privatePropertyjust so people can search it online more easily.
Collisions of Imported Types
- Introducing an error when types conflict with local type names.
import { foo } from "./stuff";
export type foo = foo;- Breaks legitimate errors in
firebase-firestore,glimmer,skype,vscode.- VS Code examples seemed suspicious.
- The general pattern is useful when running with
isolatedModules, but there's no reason to use the same name. - This is a breaking change, but the break seems legitimate, existing code seems wrong, and the fix is simple.
Ryan Cavanaugh (@RyanCavanaugh) has the other notes.
Activity
mheiber commentedon Sep 16, 2019
We implemented the proposed solution for private identifiers in
.d.tsfiles using#private(bikeshedding of the name welcome). Explanation here. Thanks for your time and for the discussion!RyanCavanaugh commentedon Sep 16, 2019
this.p = ein JS files not be treated like field declarations for the purposes of detecting these problemsinterfacepropertiesx;which means "set to undefined" in proposaldeclare x;is the logical choiceJessidhia commentedon Oct 5, 2019
That'll depend on your Babel settings as well. Babel (7) will use Define by default, but if you pass the
loose: trueoption to the transform it will use Set.