use deep quality comparison for derived updates

[cscheye]

Instead of using strict comparison on derived property changes, uses the _.isEqual method. Helps prevent triggering unnecessary change events when a derived property is not a primitive data type.

[kamilogorek]

@CristiScheye thanks for the feedback! I believe this should utilize isObjectEqual amp module – http://amp.ampersandjs.com/#amp-is-object-equal

This will reduce whole code to:

var isObjectEqual = require('amp-is-object-equal');
if (!isObjectEqual(self._cache[name], newVal) || !def.cache) { ... }

[cscheye]

@kamilogorek thanks for the pointer, and sorry for the delayed response!

[kamilogorek]

Looks good to me @CristiScheye. Could you please rebase, so it can get merged?

[cscheye]

👍

[wraithgar]

Looks good, thanks!

[latentflip]

My only concern about this is a performance hit on derived property changes. Thoughts @HenrikJoreteg ?

[HenrikJoreteg]

Hard to say what type of performance hit it would actually have, but shouldn't be significant for simple values, it should only be a hit if you're comparing more complex objects, which is probably still better than falsely triggering changes that turn into DOM updates.

This seems like a reasonable change to me. +1

[latentflip]

Oh, and just to be annoying, now that we're not using amp anymore, amp-is-object-equal will need to be lodash.isequal :/

[HenrikJoreteg]

Easy fix, though. But yeah, we should swap that out.

[flipside]

Saw this so I decided to update #116. it allows a type to be specified for derived properties and if it exists to use the dataType compare method which defaults to lodash.isequal via _getCompareForType.