Add notes for May 12

2016-05/may-12.md

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+## May 12 ([discuss](https://github.com/reactjs/core-notes/pull/14))
+
+### Attendees
+
+* [Alex](https://twitter.com/alex_frantic) (React Native)
+* [Ben](https://twitter.com/soprano) (React)
+* [Christoph](https://twitter.com/cpojer) (Jest)
+* [Christopher](https://twitter.com/vjeux) (React Native)
+* [Dan](https://twitter.com/dan_abramov) (React)
+* [Jim](http://github.com/jimfb) (React)
+* [Paul](https://twitter.com/zpao) (React)
+* [Sebastian](https://twitter.com/sebmarkbage) (React)
+* [Shayne](https://github.com/shayne) (React Native)
+* [Tom](https://twitter.com/tomocchino) (React)
+
+### Inline Styles Update
+
+* [Christopher](https://twitter.com/vjeux) is going on a parental leave and will continue [his experiments](https://github.com/reactjs/core-notes/blob/master/2016-04/april-28.md#experimenting-with-stylesheetcreate-on-the-web) in July.
+* Don’t forget that this is tied to Facebook build asset pipeline, and is not directly applicable to React.
+* However lessons learned from this work may influence our thinking about inline styles in the future.
+
+### Error Messages
+
+* People have been complaining about [the lack of error messages in production React](https://github.com/facebook/react/issues/2686).
+* Many of them aren’t actionable anyway, but some [can be useful](https://github.com/facebook/react/issues/2686#issuecomment-218017606).
+* We might want to consider an [error code system](https://github.com/facebook/react/issues/2686#issuecomment-209171272).
+
+#### Error Code System
+
+* Babel transform annotates every callsite with a number that’s known statically.
+* Sentry (and others!) can look up that number in a map.
+* A new intern will be working on this!
+
+### New Intern!
+
+* Keyan will be working on the React team as an intern.
+* [Ben](https://twitter.com/soprano) will be mentoring him.
+* The plan is for him to work on the error code system described above.
+* Another thing he might work on is a “yellow box” a la React Native.
+
+#### Yellow Box
+
+* Where should it go? fbjs?
+* Could be a more effective vector for communication between the React core team and users of React than console warnings.
+* To be practical, we would need to have warning levels and some way of suppressing them.
+* This is just an idea, the details would need to be fleshed out.
+
+### `shouldComponentUpdate()` Breaks Context
+
+* A [longstanding issue](https://github.com/facebook/react/issues/2517) with a very long thread.
+* [Sebastian](https://twitter.com/sebmarkbage) has been thinking about this (just this morning!)
+* With the [incremental reconciler](https://github.com/facebook/react/issues/6170), we think we’ll solve this.
+
+#### Can We Fix It Now?
+
+* It will make things a lot more inefficient.
+* Only some libraries use context for dynamically updating values, but enabling deep subscriptions by default will hurt performance for everyone.
+
+#### Hacky Workaround
+
+* For now, React Router 3.0 adds a hacky [workaround](https://github.com/reactjs/react-router/blob/5f3387a91d427aec1368e68cd9605797aa076bb7/modules/ContextUtils.js).
+* [@taion](https://github.com/taion) plans to pull it out in a generic module for other affected libraries.
+* Nobody is really happy about it, but hopefully it should be easy to pull it out later.
+* It [uses mixins](https://github.com/reactjs/react-router/issues/3439#issuecomment-217887475) so it’s easier to pull it out, and it doesn’t trash React DevTools view.
+* Hopefully eventually React fixes this, and React Router can <s>unpublish</s> stop using that package.
+
+### Incremental Progress vs Long-Term Vision
+
+* Long-term ideas and features often block incremental and external contributions.
+* We might want to spend more time just supporting features the community is asking for, even if we don't use them.
+* One concern is that the proposed solution often will leave us in a worse place than where we were before.
+* This is often not obvious in the beginning, and unfortunately a lot of work may get done before we realize this.
+
+#### Focus on One Thing
+
+* Maybe as a team we can focus on one area at a time.
+* For example, let’s just do one thing, do it well, and ship it.
+* Better than letting ourselves get overwhelmed.
+
+#### Avoid Wasted Effort
+
+* We can focus on external needs, but we also need to make sure that external folks are willing to support our needs internally.
+* This requires that we better communicate our needs and priorities.
+* There’s a long unwritten list of constraints, and we often reactively provide that list.
+* But it’s hard for contributors to know before they work on their big PR what that list is.
+
+#### RFCs
+
+* We should adopt an RFC process!
+* Long discussions should start before folks submit a PR.
+* In some cases, they can start after, but not in the PR itself.
+* Let’s use the [Rust](https://github.com/rust-lang/rfcs/blob/master/libs_changes.md#is-an-rfc-required) / [Ember](https://github.com/emberjs/rfcs#when-you-need-to-follow-this-process) RFC process.
+
+### Snapshot Testing
+
+* [Cristian](https://github.com/kentaromiura) in London is working on [snapshot testing](https://github.com/facebook/jest/pull/1000) in Jest.
+* [Ben](https://twitter.com/soprano) has been prototyping a full React test renderer that can render everything both on React Native and DOM.
+* Unlike shallow renderer, it is stateful and renders deeply.
+* Things won’t actually render to React Native or to the DOM, but rather to an intermediate representation.
+* This will give us the ability to diff representations.
+* (Basically we’re pretty-printing JSX and then doing textual diffs.)
+* It is not clear if the intermediate representation should include information about composite components (the “DevTools tree”).
+* Maybe this could be configurable.
+
+------------
+
+Please feel free to discuss these notes in the [corresponding pull request](https://github.com/reactjs/core-notes/pull/14).