add Ref with react ref api about react-powerplug

[egoarka]

Check this out: https://codesandbox.io/s/4z26pmkp87
not sure that it is safe to use

[xialvjun]

No, you should not use SFC. Using SFC, it's safe, but it's slow.
Use Component instead.

export class Ref extends Component {
  ref = React.createRef();
  render() {
    return this.props.children(this.ref);
  }
}

And besides, another feature request:

export class Instance extends Component {
  constructor(props) {
    super(props);
    props.init && props.init(this);
  }
  render() {
    return this.props.children(this);
  }
}

const list = [xxxx];
const to_render = <Instance init={ins => ins.audios = {}}>
  {ins => <ul>
    {list.map(item => <li key={item.id}>
      <audio preload="none" src={item.url} ref={ele => ins.audios[item.id] = ele} />
      <button onClick={e => ins.audios[item.id].play()}>play</button>
    </li>)}
  </ul>}
</Instance>

Instance is not only a Multi Ref Component, in fact, with it, we can do everything, like cache previous state, define lifecycles...

[TrySound]

I'd say you should go with classes :) Component instance is bad abstraction because implementation detail is part of the api.

[xialvjun]

@TrySound you are talking about Instance component?
But to write a Component Class, I need to go out of JSX, write the class, then use it in JSX.
With Instance component, I can just write it in JSX.

Why I think just write in JSX is important?

Because write a class is much harder than write a vnode: well, write a class is not hard, but compared to write a vnode, you'll feel it much harder.

[TrySound]

I know it's hard, but mutable instance with methods as first class citizen is not the best api for immutable tree. Instance has a lot of stuff which is implementation detail in context of render prop. I would prefer to mutate state with values you need.

[xialvjun]

But in some cases, we do really need mutable instance which won't cause a update when changing its state.

Well, without Instance, how to make a Multi Ref Component

[TrySound]

Show me the case please

[xialvjun]

Code in #126 (comment) showed the case.
Copy it here:

const list = [xxxx];
const to_render = <Instance init={ins => ins.audios = {}}>
  {ins => <ul>
    {list.map(item => <li key={item.id}>
      <audio preload="none" src={item.url} ref={ele => ins.audios[item.id] = ele} />
      <button onClick={e => ins.audios[item.id].play()}>play</button>
    </li>)}
  </ul>}
</Instance>

[TrySound]

It's okay to mutate state.

const list = [xxxx];
const to_render = (
  <State initial={{ audios: {} }}>
    {({ state }) => (
      <ul>
        {list.map(item => (
          <li key={item.id}>
            <audio preload="none" src={item.url} ref={ele => state.audios[item.id] = ele} />
            <button onClick={e => state.audios[item.id].play()}>play</button>
          </li>
        )}
      </ul>}
  </State>
)

Or if you don't want to mutate state you may create mutable object on instance. Just don't pass instance with all its methods. Operate with data only here, mutable and immutable.

class Mutable extends React.Component {
  mutable = this.props.initial;

  render() {
    return this.props.children(this.mutable)
  }
}

[xialvjun]

Well, it's a debate between two API offering philosophy: I offer these apis because I can and I offer these apis because you just need them.

In fact, I don't know which philosophy is better... -_-!!!!

Component Mutable is OK.

Choose which one you feel comfortable. :)