Deprecate getWithDefault

[chrisrng]

Rendered

[NullVoxPopuli]

I'm a fan. This is codemodable. 👍

[xg-wang]

Should EmberObject.getWithDefaultalso be deprecated?

[snewcomer]

let result = get(obj, 'some.key') || defaultValue;

Is this an alternative option? Also, should the codemod require get or can we use plain property accessors?

[chrisrng]

I think it makes sense to use get to minimize behaviour differences

[buschtoens]

Codemodding paths and interpolated paths will be significantly harder as well:

getWithDefault(obj, 'foo.bar');
getWithDefault(obj, `foo.${key}`);
getWithDefault(obj, path);

I'd also suggest to codemod towards get and then potentially run another codemod from get towards native accessors in the future.

[simonihmig]

FWIW, there is already a codemod for get() to native: https://github.com/ember-codemods/es5-getter-ember-codemod. (at least for simple properties, no paths yet)

And someone even suggested covering getWithDefault() already: ember-codemods/es5-getter-ember-codemod#1 😝

[rwjblue]

Thanks for working on this @chrisrng! Seems like a good idea to me...

[EWhite613]

I don't think to have a code mod to do the following is really useful.

let result = get(obj, 'some.key');
if (result === undefined) {
  result = defaultValue;
}

I would suspect most people would modify the code mod to use their own util or use something like lodash (if they want that default behavior). Cause having one line turn into 4 while also increasing the complexity is not something I would think people would want in their code

[chrisrng]

FYI @steventsao added this to eslint-plugin-ember ember-cli/eslint-plugin-ember#594

[steventsao]

I don't think to have a code mod to do the following is really useful.

let result = get(obj, 'some.key');
if (result === undefined) {
  result = defaultValue;
}

I would suspect most people would modify the code mod to use their own util or use something like lodash (if they want that default behavior). Cause having one line turn into 4 while also increasing the complexity is not something I would think people would want in their code

Yeah turning one assignment into a block would not be ideal. But this can be a one-liner, right?

// I imagine the value of `get()` is cached 
const result = get(obj, 'some.key') === undefined ? get(obj, 'some.key') || defaultValue;

Optional chaining and nullish coalescing:

const result = obj.some?.key ?? defaultValue;

[chriskrycho]

@steventsao @EWhite613 Codemodding it in the safest way possible is the important bit here. You can definitely do it with a ternary, and that's fine with me as well. I suggested this particular output to @chrisrng because it seemed the clearest to me; a ternary would also be fine but does impose the slight extra cognitive overhead of having to think about the caching question when you're reading it. I'm not married to the let + if block for sure.

[rwjblue]

We discussed this in the Ember core team meeting today, and the team is broadly in favor of moving forward here. I think we need a few (hopefully minor) tweaks here.

We will likely need to at least mention nullish coalescing in the transition path, but also need to properly balance that against both the differences in getWithDefault's behavior (only uses undefined instead of null + undefined) and how destructuring with assignment would work (which uses "falsey" rules.

@chrisrng - Concretely, would you mind taking a crack at tweaking the transition path section to incorporate some messaging about destructuring, as well as some examples using nullish coalescing (basically explaining that there is a difference between it and getWithDefault, but if a particular case didn't care about the difference how it would look) and destructuring with defaults (same basic caveat, destructing with default uses "falsey" semantics).

[mixonic]

Some text should be added here: Ember can only suggest nullish coalescing syntax once Ember CLI supports that syntax out of the box. It should be supported in a stable release of Babel, but additionally we need to be sure that ember new includes that version of Babel.

And the deprecation instructions should explain how to get the proper version installed.

[rwjblue]

We discussed this in todays core team meeting and have decided to move this into final comment period.

[steventsao]

fyi adding codemod https://github.com/steventsao/ember-no-get-with-default-codemod