sketch.md

Making unique-id a importable function

The Use Cases

import { uniqueId } from "@ember/???";

<template>
  {{#let (unique-id) as |id|}}

  {{/let}}
</template>

import { uniqueId } from '@ember/???';

class MyThing {
  id = uniqueId();
}

The Constraints

1. The behavior of (unique-id) in classic mode must be the same as the behavior of uniqueId() in <template> mode.
2. The uniqueId function must be the same function in both use-cases described above.
3. The result of uniqueId() in a <template> must not change after the expression was initially evaluated.
4. Other importable "helpers": a. hard constraint: should eventually come from the same package name (or, some coherent package structure) b. soft constraint: people will find it weird if we ship uniqueId but not other similar helpers that are in a similar predicament.
5. Modifiers and components should also ultimately be imported from a coherent package structure that includes whatever we do here.

Importable Things

Ember.Template.Helpers

Name	Type	In <template>?	Importable?
action		☠️	☠️ Uses this from template
array	pure helper	😀	✔️
hash	pure helper	😀	✔️
component		😀	✔️
- takes dynamic string	internal	☠️	☠️
- take a component	???	😵‍💫	???
helper	???
modifier	???
concat	pure helper	😀	✔️
debugger	control flow	😀	✖️
each	control flow	😀	✖️
each-in	control flow	😀	✖️
fn	probably keyword	😵‍💫	😵‍💫
get	pure helper	😀	✔️
has-block	control flow	😀	✖️
has-block-params	control flow	😀	✖️
#if	control flow	😀	✖️
if	control flow	😀	✖️
#unless	control flow	😀	✖️
unless	control flow	😀	✖️
in-element	internal component	😀	✖️
input	classic component	☠️	✖️
let	control flow	😀	✖️
link-to	classic component	☠️	✖️
log	???
mount	control flow	😀	✖️
mut	keyword (references)	☠️ ?
on	modifier	😀	✔️ (maybe keyword)
outlet	control flow	😀	✖️
page-title	???
textarea	classic component	☠️	✖️
unbound	legacy	☠️	✖️
unique-id	non-deterministic helper	😀	✔️
yield	control flow	😀	✖️

NOTE: inline if and unless are control flow because they "auto-arrow" their expressions.

Importable Candidates

Meaningful in JS

Name	Type	In <template>?	Importable?	Meaningful in JS?
concat	pure helper	😀	✔️	✔️
log	non-deterministic helper		✔️	✔️
unique-id	non-deterministic helper	😀	✔️	✔️

Not Meaningful in JS

Name	Type	In <template>?	Importable?	Meaningful in JS?
mut	keyword (references)	☠️ ?		✖️
on	modifier	😀	✔️ (maybe keyword)	✖️
page-title	non-deterministic control flow			✖️

Unsure

Name	Type	In <template>?	Importable?	Meaningful in JS?
array	pure helper	😀	✔️	🤔
hash	pure helper	😀	✔️	🤔
get	pure helper	😀	✔️	🤔

Maybe we want these to be keywords because they are effectively literal notation for objects and arrays.

Built-In Components

These are currently implemented as special Glimmer resolution rules, but we don't want to make them keywords in <template>, so they need to be importable.