<Jan> Rniwa proposing we go through Domenic’s prioritized list of issues

Domenic: let’s start with some easy ones
... seems like “restrict to secure contents” is not going to happen

[no one objects]

Domenic: I’ll note that in the thread

annek: on attributeChangedCallback order, sounds like we can’t agree on an order

rniwa: order is an interop issue

annek: it’s going to take a long time before Gecko gets around to (preserving stable attribute order)

elliott: there’s stuff to be sacrificed there
... what webkit does doesn’t end up with memory optimization
... we’re asking Gecko to reduce the effectiveness of their memory optimization
... Chrome and WebKit both agree

elliott: there’s no interop here, so if we change it, nothing breaks
... MutationObserver is going to give you totally different order in diff browsers

domenic: propose: keep the order that’s in the spec, general willingness to converge on determinism

rniwa: ok, but I wouldn’t necessarily block the other browsers from implementing custom elements (by forcing determinism)

elliott: doesn’t seem like a big enough win for Gecko

<annevk> sorry dglazkov :-(

Travis: try again

<annevk> no jokes this time I guess

<dglazkov> hangouts_queue.pop()

(Travis joins video chat)

rniwa: should we tackle “parse <slot> like <template>”?

annek: it sounds like nobody is really interested in making parser changes
... i’m tempted to punt on the whole thing
... ideally a custom element could replace a <thead>, etc., but...

rniwa: I thikn that this would be really risky
... we’ve seen elements in the wild with a dash in their name, so changing this would be risky

domenic: this would be nice, but probably not worth it
... nobody seems to be strongly advocating for it

annek: this is probably okay as is

travis: is there a good workaround?

annke: you can always just use the DOM API to restrict your tree instead of the parser

annek: but that’s a workaround
... or you could use custom elements for everything, reinvent all the elements

elliott: that’s funny, html tables is missing column spans, that’s the only reason people use real tables
... the generalized solution we’d like to pursue is a meta tag that lets you opt into a more streamlined parser

annek: an XML5 (?) parser

elliott: we’ve spend so much time band-aiding this thing, that’s why we never went there

annek: in general, that’s a fine plan

travis: sounds like versioning to me

annek: sounds more like strict mode

elliott: the nature of such a thing is off topic

annek: it is hard

rniwa: alternative is to have an attribute to add an element to a slot

domenic: certainly not v1, but any reason why that’s not a good idea

rniwa: it kind of violates the fundamentals of the element

annek: do you use display: contents on it, and then what does that mean? sounds like v2

rniwa: an attribute way of adding a slot might be a v2 thing

elliott: if this is popular, someone will write a library to (implement this feature), and that will be a signal to do this

annek: let’s move to the top of the list, issue 308: should we use “display: contents"?
... I’m going to say “yes"
... … Gecko has an implementation of display: contents.

rniwa: We haven’t done this yet, but our intention is to do so

domenic: our position: reasonable semantics, main concern is that this adds a lot of implmentation
... would delay getting this into users’ hands

travis: can someone restate the problem

annek: can the <slot> element itself end up in the final layout/flat tree

if it ends up there, you can style it; if not, you can’t do anything with it

travis: iframes are sort of like super-slots, and they’re independently styleable
... but its background color doesn’t matter, because it gets replaced

(as jan) I haven’t seend the need for this

travis: maybe it shouldn’t have a particular representation

annek: if blink ships with its current idea of not having it in the layout tree, ...

and then changes some months later...

elliott: this doesn’t really work, you could end up styling the slot by mistake
... you wouldn’t want to ship this
... any style applied to the slot is a no-op

rniwa: we’re changing the behavior as we speak

<Domenic_> https://github.com/w3c/webcomponents/issues/308#issuecomment-204198578 outlines elliott's concerns in more detail

rniwa: we also support computed styles on the slot
... principle is this: there are real use cases that display: none would be ignored
... that’s confusing
... every other kind of element is styleable

elliott: it’s not clear to me that eveyrone has that expectation

travis: but the slot will be there if you go exploring (in the DOM)

elliott: yes, the slot is there, but you can’t put a border on it, or padding, or margin...
... assuming display: contents, you could put an inheritable property on it
... if I put :before and :after on the slot, do they apply?

rniwa: this is an issue with display: contents in general

elliott: I think display: contents is a confusing feature

rniwa: if you want to object to that feature, you could do that with W3C

elliott: I have
... coupling Shadow DOM to a feature that involves…

rniwa: elliott and Tab (Atkins) both work for the same company, and should (be on the same page)

elliott: there’s not concensus within Google that we need this feature
... there are a lot of edge cases that would be broken in v1

annek: if we don’t do this in v1, we can’t add it later

elliott: the only way to solve this in the future would be to introduce a new CSS property

annek: there’s an element in the tree, and then it disappears from the tree, we don’t have anything else like that

domenic: can you style the <meta> element?

(someone) yes

annek: it sounds like we add a style for style slot in the future that’s special, or do display: contents now

elliott: it’s not clear that everyone’s agreed to the details of everything (Tab) is implying

domenic: figuring out suitable semantics for everything is what we’re not excited about

annek: if you do display: contents, you can have pseudo-elements

<annevk> http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A...%3Cstyle%3E%0Adiv%20%7B%20display%3Acontents%20%7D%0Adiv%3A%3Abefore%20%7B%20content%3A%22X%22%20%7D%0Adiv%3A%3Aafter%20%7B%20content%3A%22X%22%20%7D%0A%20%3C%2Fstyle%3E%0A%3Cdiv%3Etest%3C%2Fdiv%3E

hayato: because shadow root is removed from the tree, slot is removed from the tree
... there’s a dilemma for that
... problem is we have to make the <slot> element an element
... can we have a new type of element for <slot>?
... we can style the parent elements of slots

rniwa: i think the problem is consistency. <slot> is a weird element
... can’t get computed style, but things inside of it would be shown, it’s exotic

annek: we could have a <slot> node instead of an element
... would it still have to be created by the HTML parser?
... if that’s the requirement, then it does need to be an element

(someone) let’s not go there

travis: i don’t have a problem with <slot> being an element
... i like having display: contents so that it’ll be there down the road

annek: some engines can ship display: contents, some don’t, we can sort it out later

travis: it’s like the appearance property

domenic: (grimmace)

elliott: if we spec it as display: contents, and then change it to display: block, does the slotting algorithm still place things underneath it?

rniwa: it would render
... it’s as if you have an anonymous box around the lements

annek: it’s not anonymous, it’s not an element

traivs: you can give it some padding, and that would work

annek: i think it’s okay, if mozilla and webkit ship it, and blink can fix it soon enough

<annevk> https://github.com/w3c/webcomponents/issues/417: caching vs. late binding of lifecycle callbacks

annek: next: issue #417: caching vs. late binding of lifecycle callbacks

domenic: if you change callback on an element, should we call it, instead of one on the custom element you originally registered
... i’d like to close this, it’s the only big remaining custom elements problem

travis: trying to parse out the last comments on that issue

rniwa: the main problem we had was is the inconsistency
... you can change other methods on an element, but not callbacks

domenic: all elements go through a define step, including built-ins
... if i’m the browser, and change setAttribute before the built-in element is defined, that changes the behavior
... if i do that after it’s been registered, it doesn’t change the behavior
... same thing should apply to user code

travis: we should impose similar restrictions on user code by caching (callbacks) and not allowing mutability

annek: this sounds nice, until you consider subclasses
... the subclass cannot change those things
... mozilla has given up on finding any consistency here

domenic: if you want to be completely consisten with regard to subclassing you have to protect (invariants?)

[discussion]

elliott: you shouldn’t do dynamic customization on a per element basis

domenic: you should have to opt-in to per-element customization
... you can’t overwrite the click method of an <input>

[discussion]

rniwa: we could just freeze those attributes once define is called

domenic: i don’t like modifying user classes
... we just got away from that

elliott: how do you freeze these?

rniwa: we can store the callbacks at define time
... there concern is that the user can modify it, all othermethods work, but not these (callbacks)

travis: domenic pointed out that the user can try to modify all sorts of platform behavior, and that doesn’t work

domenic: when the platform wants to create an array, it doesn’t call user code, it just creates an array

[discussion of @@species as an example of user code being called from platform code]

travis: the question is: is this an extension point that we want to create

rniwa: if that’s the case, we should go back and make these symbols again
... then there’d be less confusion that these are special

travis: symbols are not immutable

elliott: symbols would have different author expectations

<annevk> Element.attributeChanged

<annevk> "attributeChangedCallback"

<annevk> (latter is two characters extra, but I guess you typically don't need the quotes)

annek: i think we have rough consensus, and Apple would be slightly sad

domenic: these callbacks (on custom element classes) are kept there for subclasses

rniwa: i’m not okay with it, but let’s just move on

elliott: let’s move on, what’s next

https://github.com/w3c/webcomponents/issues/477:

rniwa: exposing the element inside a closed shadow root doesn’t make sense

annek: since open trees are exposes here and there, currentscript can expose them?
... how do we solve this, even for the closed case?
... it doesn’t seem ideal that you can’t get a reference to yourself

rniwa: it’s hard to imagine a custom element accessing a random script inside it and getting a reference to itself

elliott: script type=“module” runs in a separate scope, right?

domenic: corret

elliott: document.currentScript is kind of bizarre
... in an HTML Import, document.currentScript ends up referencing the script that’s being imported
... we should have a variable within script type=“module” for this instead of a currentScript global

domenic: we can let it be null in Shadow DOM, especially closed, potentially open, is that right?

elliott: there are use cases where you need to be attributes on a the <script> tag directly

annek: it’s reasonable that those libraries get rewritten for the brave new module world
... maybe we should just ban this API

rniwa: that’s a good way to go, esp. since no one’s implemented script type="module"

travis: the fact that we have this global property and that’s sort of working already, i feel that we shouldn’t do any work on it to protect closed Shadow DOM
... closed Shadow DOM isn’t a security barrier anyway
... this is just another way to work around it
... if I really want that strong security, we have to go with that isolated approach
... not doing anything with currentScript and let it have this weird access seems like a bizarre case

annek: we should resolve this as returning null
... this is the least objectionable path
... moving on

<annevk> https://github.com/w3c/webcomponents/issues/355: use CSS containment features by default

elliott: are we okay with saying that if you put an absolute element inside your element, and position it outside your element, is it okay if it gets clipped (because of CSS containment)?
... intention of doing this is to state an opinion about the direction we should be moving
... if you encourage authors to place elements more visually, you get a simplified implementation and your code can be faster
... we could encourage authors to be fast by default

domenic: this was just an opportunity to introduce a new direction

rniwa: this would simplify delay introducing Shadow DOM in WebKit
... we don’t have this implemented

annek: how many browsers implement `contain`?

[discussion]

rniwa: i think doing this for Shadow DOM is the wrong approach

dan: we don’t about this feature being the default

annek: sounds like we have consensus (to punt this)

<annevk> https://github.com/w3c/webcomponents/issues/186: integrating callback invocation with IDL and editing operations

domenic: [describes a proposal related to IDL]

rniwa: I think this is a great thing to do

travis: i agree
... it would be great to have this declaratively

domenic: okay
... i’ll figure it out, it’s just going to be a pain

<annevk> https://github.com/w3c/webcomponents/issues/468: provide a mechanism for adding default/"UA" styles to a custom element

domenic: now that we got rid of /deep/, there’s no way to style an element like this

rniwa: only question is whether we take a string, or what type?

elliott: it can’t be inline style
... there’s also a proposal to have constructible stylesheets
... if we do this to use a string, then we can use constructible stylesheets when they’re finished
... blocking on stylesheet objects seems silly, that’s a big project and a ways out

travis: this isn’t blocking v1, right?

domenic: we could add this

elliott: we were hoping this would be just like attaching a shadow root, then appendChild’ing a a style element

travis: i was seeing this as styling the custom element itself

domenic: the :host selector would style the element itself and the descendants

elliott: it doesn’t style the descendants

rniwa: we need to create a new context in which these (styles?) are evaluated
... we’re somewhat skeptical of this feature, it seems redundant
... we already implemented optimization that if you define the same style in a shadow root, and it gets reused across many elements, we reuse...

domenic: this would let you do styles without having to add a shadow root
... i would like this to be at the same level of the cascade as UA styles
... this is currently impossible

[discussion]

elliott: providing a feature like this allows a framework to say, “all elements in my framework are block”, which I think is beneficial

rniwa: i don’t think we object to this, but i don’t want to block the rest of the custom elements API on this

annek: this shouldn’t block shipping minimum viable product

<annevk> https://github.com/w3c/webcomponents/issues/288: `slotchange` event

domenic: this doesn’t block shipping v1

annek: i think we all agree on using MutationObserver timing
... i’m assuming it wouldn’t bubble?

elliott: are there any other microtask-timed events?

<smaug> (does bubble or not really matter?)

travis: promises are microtasks timed

<smaug> (and no, this would be the first microtask timed event)

rniwa: maybe this microtask is the timing you want to use for new async-type events

annek: full-screen events don’t use task-timing

<smaug> (and we need to remember that microtask != async from UA point of view. /me goes back to doing something else.)

elliott: this seems like we’re inventing a new technology, do we intend to do that

(someone) want about “blur"?

annek: depends on the engine

elliott: i’m not objecting to the timing here, unless we think this is one-off thing for slotchange

domenic: this is mutation-to-the-DOM timing

(someone) why isn’t this is a MO?

travis: this generalizes it, to the point where we may not want it to be a MO

annek: 1 we have multiple mutation records
... 2 a record is expected to carry sufficient data to reply what happened, which someone people don’t want here
... 3 if you think of Shadow DOM as a layer on top of DOM and should use DOM architecture
... the proposal is tied to how much insert/remove behave
... given not wanting to expose too much data, i’m okay with this as an event

travis: the event and how you expect it to look after processing queued records, is that defined?

annek: i’ve been waiting for this call to be over

elliott: when do we queue the event?

[discussion]

elliott: let’s just do this for v1, and see what authors

<rniwa> woot! so productive :D

<annevk> yeah this was great

<annevk> thanks everyone

<dglazkov> \o/

<rniwa> jan: thanks for scribing!

This is scribe.perl Revision: 1.144  of Date: 2015/11/17 08:39:34  
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Got date from IRC log name: 05 Apr 2016
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