Merge pull request #22 from reactjs/gaearon-patch-1

Add notes for June, 30

2016-06/june-30.md

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+## June 30 ([discuss](https://github.com/reactjs/core-notes/pull/22))
+
+### Attendees
+
+* [Ben](https://twitter.com/soprano) (React)
+* [Dan](https://twitter.com/dan_abramov) (React)
+* [Jim](http://github.com/jimfb) (React)
+* [Keyan](https://twitter.com/keyanzhang) (React, intern)
+* [Paul](https://twitter.com/zpao) (React)
+* [Sebastian](https://twitter.com/sebmarkbage) (React)
+* [Tom](https://twitter.com/tomocchino) (React)
+
+### Fiber Demo
+
+* If you missed what Fiber is, [look here](https://github.com/reactjs/core-notes/blob/master/2016-06/june-23.md#update-on-fiber).
+* Not very exciting.. but it can render a `<div>`!
+* Basically this is all that [Sebastian](https://twitter.com/sebmarkbage) showed us so far.
+* You can find the demo [here](https://github.com/facebook/react/blob/24dfb56113a214d98f29f69e2c26f67d7e947067/examples/fiber/index.html) but you’d need to compile React DOM to point to the [fiber version](https://github.com/facebook/react/blob/24dfb56113a214d98f29f69e2c26f67d7e947067/src/renderers/dom/fiber/ReactDOMFiber.js).
+
+### Update on `createClass` → ES classes
+
+* We are moving towards not using `createClass` in the internal Facebook components.
+* [Keyan](https://twitter.com/keyanzhang) is working on an open source [codemod](https://github.com/reactjs/react-codemod/pull/54) to automate the transition.
+* The codemod converts `createClass` calls to ES classes with experimental [property initializers](https://github.com/jeffmo/es-class-fields-and-static-properties) proposal and Flow.
+* We *don’t* officially recommend this yet because the proposal has not advanced yet but we want to dogfood it internally.
+* There are more things to figure out with Flow (e.g. we might need to annotate state properties).
+* [Dan](https://twitter.com/dan_abramov) ran the codemod that removes one very common mixin we had, so now we have more convertible classes.
+* It is essential that we add some version of [`PureComponent`](https://github.com/facebook/react/pull/6914) to React because a lot of components use `PureRenderMixin`.
+
+### `React.PureComponent`
+
+#### Naming
+
+* We’ve been assuming we’d call it `React.PureComponent`.
+* However “pure” really means something different in computer science.
+* What we try to express is that component `props` are immutable so the output is safe to memoize.
+* Other suggestions: `MemoizedComponent`, `MemoizableComponent`.
+* It’s hard to spell!
+* We *don’t* want people to use it everywhere so more complicated name might be fine.
+* We can bikeshed on this forever.
+
+#### Heuristics
+
+* It seems that [proposed heuristic generated a lot of confusion](https://github.com/facebook/react/pull/6914) and [potential issues](https://github.com/facebook/react/pull/6914#issuecomment-229574637).
+* We can drop the heuristic from the proposal and just get the class in. Then decide later.
+
+### Splitting [Addons](https://facebook.github.io/react/docs/addons.html)
+
+* After the internal `createClass` deprecation, can we drop the addons?
+* We [haven’t](https://github.com/facebook/react/pulls?q=is%3Apr+reacttransitiongroup+is%3Aclosed) been maintaining `ReactTransitionGroup` and other addons well.
+* We should transfer ownership to folks that are actually relying on them.
+* Almost everything can be decoupled except `Perf` and `TestUtils`.
+* This should happen before [flat bundling](https://github.com/facebook/react/issues/6351).
+* Should we move `React.createFragment` into React?
+  - No, this was an upgrade path, shouldn’t need to use it anymore.
+  - It could have been the way you specify render methods without a single return value but we didn’t implement this.
+* [Paul](https://twitter.com/zpao) and [Dan](https://twitter.com/dan_abramov) will come up with a plan for each addon.
+
+### React Hot Loader 3
+
+* It is popular in the community but the last stable version doesn’t work with functional components.
+* There is a new version that solves these problems but it isn’t quite stable yet.
+* [Dan](https://twitter.com/dan_abramov) will take a week to fix a few issues and release a stable version with docs.
+
+### Releasing 15.2.0
+
+* [Paul](https://twitter.com/zpao) planned to release today.
+* [Dan](https://twitter.com/dan_abramov) noticed it would be better to [deduplicate](https://github.com/facebook/react/issues/7152) the new DOM unknown attribute warning. 
+* We will let the community fix it and then cut 15.2.0.
+* [Jim](http://github.com/jimfb) wrote about the reasons and the strategies for fixing this warning [in the related gist](https://gist.github.com/jimfb/d99e0678e9da715ccf6454961ef04d1b).
+* Some useful discussions about this change: [erikras/redux-form#1249](https://github.com/erikras/redux-form/issues/1249), [Hacker0x01/react-datepicker#517](https://github.com/Hacker0x01/react-datepicker/issues/517).
+* We won’t do a blog post about this release (and about most patch and minor releases in general).
+* Instead, you can find changes in the [changelog](https://github.com/facebook/react/blob/master/CHANGELOG.md#1520-july-1-2016).
+
+------------
+
+Please feel free to discuss these notes in the [corresponding pull request](https://github.com/reactjs/core-notes/pull/22).