Adding support for enums

[Nicolò Ribaudo]

Have you seen https://github.com/rbuckton/proposal-enum? The champion is a
TypeScript member, so he already had experienc with enums.

On Sun, Jun 10, 2018 at 5:44 PM kai zhu <kaizhu256 at gmail.com> wrote:

>  In Redux, there are actions, which are strings, that get passed to a
> reducer, which mutates the states.  My coworker and I inadvertently added
> the same action name, "LOADING" on the same page, but in two different
> files.  This led to a bug when both my modal and his search results would
> be loading at the same time, but since they were never both visible, we
> didn't catch the bug.
>
>
> can you explain in code how either enum or symbols could solve your
> problem?  reading up on how reducers work @
> https://redux.js.org/basics/reducers#handling-more-actions, i'm guessing
> the problematic code looks like the following.
>
> ```js
> // module spinner.js
> var action = {
>     type: 'LOADING',
>     ...
> };
>
> // module search.js
> var action = {
>     type: 'LOADING',
>     ...
> };
>
> // module main.js
> switch (action.type) {
> case 'LOADING':
>     // inadverdently run both
>     // spinner-loading and
>     // search-result-loading actions
>     ...
>     break;
> }
> ```
>
> its not obvious to me how enums/symbols could be use in a less-complicated
> solution, than simply renaming action.type in your case with more
> descriptive names that won’t collide (e.g. 'LOADING_SPINNER',
> ‘LOADING_SEARCH_RESULT').
>
> kai zhu
> kaizhu256 at gmail.com
>
>
>
> On 10 Jun 2018, at 11:26 AM, Michael J. Ryan <tracker1 at gmail.com> wrote:
>
> Just use symbols for your action type
>
> On Sat, Jun 9, 2018, 14:21 Doug Wade <douglas.b.wade at gmail.com> wrote:
>
>> Hello friends!
>>
>> I had a bug the other day on my team.  We use redux
>> <https://redux.js.org/> to manage the state on our application
>> <https://resumes.indeed.com/>, which is maintained by a large team.  In
>> Redux, there are actions, which are strings, that get passed to a reducer,
>> which mutates the states.  My coworker and I inadvertently added the same
>> action name, "LOADING" on the same page, but in two different files.  This
>> led to a bug when both my modal and his search results would be loading at
>> the same time, but since they were never both visible, we didn't catch the
>> bug.  My coworker refactored his feature, and broke my feature, such that
>> rather than displaying a spinner, we went straight to an empty results
>> page, even when there were results.
>>
>> In other languages, like the language I use most at work, Java, we would
>> instead use a language construct called an enum
>> <https://en.wikipedia.org/wiki/Enumerated_type> in this situation so
>> that the two different sets of actions weren't equal to each other.  I did
>> some research into some previous discussions on this
>> <https://esdiscuss.org/topic/enums> topic, and it seems like the
>> discussion has been broadly in favor of it. I also noted that enum is a reserved
>> keyword
>> <https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Lexical_grammar#Keywords>,
>> which indicates some intention to add enums to the language.
>>
>> As such, I've spent some time working on a proposal
>> <https://github.com/doug-wade/proposal-enum-definitions> for adding
>> enums to ECMAScript. It is very heavily based on the work by rauschma
>> <https://github.com/rauschma/enums/blob/master/enums.js>, stevekinney
>> <https://github.com/stevekinney/ecmascript-enumerations> and rwaldron
>> <https://github.com/rwaldron/proposal-enum-definitions>. I wasn't sure
>> if I was using all the right words when writing the proposal, so to help
>> express myself better, I also spent some time writing a babel plugin
>> <https://github.com/doug-wade/babel/tree/babel-plugin-proposal-enum>
>> that uses a polyfill <https://github.com/doug-wade/enum-polyfill>
>> against which I've written a small test suite
>> <https://github.com/doug-wade/enum-unit-tests> (if you would like to run
>> them, you'll need to link the polyfill and the babel plugin into the
>> tests). Please do not take these as any indication of "done-ness", I wrote
>> them to understand how I would expect an enum in javascript to behave, and
>> am willing and eager to make changes as I get suggestions. I do, however,
>> feel I have done as much as I can on my own, and would like help in
>> considering the proposal, especially whether it contains any footguns,
>> undefined behavior, or things that would be surprising to newer developers,
>> and helping me identify what work is to be done to make this a "real"
>> proposal.
>>
>> All the best,
>> Doug Wade
>>
>> _______________________________________________
>> es-discuss mailing list
>> es-discuss at mozilla.org
>> https://mail.mozilla.org/listinfo/es-discuss
>>
> _______________________________________________
> es-discuss mailing list
> es-discuss at mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
>
> _______________________________________________
> es-discuss mailing list
> es-discuss at mozilla.org
> https://mail.mozilla.org/listinfo/es-discuss
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.mozilla.org/pipermail/es-discuss/attachments/20180610/d3bb9baa/attachment-0001.html>