Recompose: [HOC suggestion] withPropsOnDeepChange

[gersomvg]

See this use case:

Let's say we have these props:

{
  items: [{ id: 1, name: 'foo' }, { id: 2, name: 'bar' }],
  hiddenId: 1,
  someOtherVeryComplexObject: { ... },
}

And we want to do something like this:

withPropsOnChange(
  (props, nextProps) => {
    const subset = ['items', 'hiddenId']
    // Lodash 'isEqual' provides deep comparison
    return !_isEqual(_pick(subset, props), _pick(subset, nextProps))
  },
  props => ({
    itemsWithoutHidden: _filter(({ id }) => id !== props.hiddenId, props.items),
  })
),

It would be nicer to write it like this:

withPropsOnDeepChange(
  ['items', 'hiddenId'],
  props => ({
    itemsWithoutHidden: _filter(({ id }) => id !== props.hiddenId, props.items),
  })
),

I'm happy to make a pull request for this, but let's see first if other people find this valuable too.

[istarkov]

Hi,

In most cases you can avoid using deep equality checks, just operate with your data in immutable manner. IMO even we all use deep equality checks sometimes I can say that for me it's really rare operation, so two-three additional lines like in your first example is not a big code overhead vs just withPropsOnDeepChange.

Also this suggestion is somehow similar to this https://github.com/acdlite/recompose/pull/120

[gersomvg]

just operate with your data in immutable manner

You mean that as long as I only do reassignments when data actually changes, object references will stay the same and will pass shallow comparison? Why didn't I realise that before :')

Edit: haha, I just realized the real power of immutability, after using it for almost a year. Mind blown.