[RFC] DOM Living Standard API

4 years ago by Benjamin Eberlei — view source

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Hi Internals,

Thomas and I are working on updating the ext/dom to add support for the
current DOM Living Standard API as standardized here:
https://dom.spec.whatwg.org/

https://wiki.php.net/rfc/dom_living_standard_api

This RFC is targeting 7.4 and contains three independent changes:

a set of new methods and interfaces that can be implemented BC as
addition to the existing ext/dom.
a removal of a few "dead" classes that are exposed to userland, but
neither documented nor containing implementation code.
a compatibility layer to switch the implementation between DOM Level 1-3
and the Living Standard in places where BC is not possible.

A pull request includes a nearly complete implementation of the new
methods, but nothing of the cleanup/compatibility yet:
https://github.com/beberlei/php-src/pull/1

We are looking forward for your feedback.

greetings
Benjamin

3 years ago by Benjamin Eberlei — view source

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On Fri, Mar 22, 2019 at 9:14 PM Benjamin Eberlei kontakt@beberlei.de
wrote:

Hi Internals,

Thomas and I are working on updating the ext/dom to add support for the
current DOM Living Standard API as standardized here:
https://dom.spec.whatwg.org/

https://wiki.php.net/rfc/dom_living_standard_api

This RFC is targeting 7.4 and contains three independent changes:

a set of new methods and interfaces that can be implemented BC as
addition to the existing ext/dom.

a removal of a few "dead" classes that are exposed to userland, but
neither documented nor containing implementation code.

a compatibility layer to switch the implementation between DOM Level 1-3
and the Living Standard in places where BC is not possible.

A pull request includes a nearly complete implementation of the new
methods, but nothing of the cleanup/compatibility yet:
https://github.com/beberlei/php-src/pull/1

We are looking forward for your feedback.

greetings
Benjamin

Hi internals,

a few month have gone by and I came back to revisit this RFC and simplify
to get something shipped.

i have updated the RFC to only include the set of new methods and
interfaces that the DOM Living Standard has implemented.

https://wiki.php.net/rfc/dom_living_standard_api

I am asking about feedback especially on the section "Implementation
Details", that explains some key differences to "PHPify" the DOM Living
Standard API to PHP and ext/dom. Do you have any comments about the
reasonability of the choices?

Also the section on "Not adopting Nodes for now" is new and I need some
feedback on this issue: To keep the proposal slim with respect to changing
existing behavior, the improved behavior of the DOM Living Standard over
Level 1-2 tof automatically adopting nodes instead of throwing a WRONG
DOCUMENT DOMexception is not considered for now. Do you think this is a
reasonable approach to go forward with?

As for the implementation, it is now in this PR
https://github.com/php/php-src/pull/4709

Looking forward for further input.

Benjamin

List of Changes to RFC:

The RFC has been updated to include a few more details about what each
new property or method does.
The new behavior of the Living Standard of automatically adopting nodes
is skipped in implementation for now to keep the existing behavior of other
manipulation methods to throw WRONG document. Workaround is still to
importNode first. Adopting nodes can be implemented as improvement later,
because it has no backwards compatibility impact.
I removed all sections on trying to achieve compatibility between old DOM
level 1-3 and the living standard, especially w.r.t. to DOMHtmlDocument
(uppercase nodeName, body property, ...). I think we can live with not 100%
compliant, ext/dom never was fully compliant. helpful would be a new
section in the docs that explains our existing differences to the spec to
users. Specifically the spec itself says that users should test existance
of features by checking for properties or methods.
The cleanup of dead / unimplemented classes is not RFC worthy and can be
done without making the RFC more complex.

3 years ago by Peter Bowyer — view source

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Hi Benjamin,

I like the proposal.

I am asking about feedback especially on the section "Implementation
Details", that explains some key differences to "PHPify" the DOM Living
Standard API to PHP and ext/dom. Do you have any comments about the
reasonability of the choices?

I don't have feedback, other than to ask what choices other languages have
made when bringing in the DOM Living Standard API?

Also the section on "Not adopting Nodes for now" is new and I need some
feedback on this issue: To keep the proposal slim with respect to changing
existing behavior, the improved behavior of the DOM Living Standard over
Level 1-2 tof automatically adopting nodes instead of throwing a WRONG
DOCUMENT DOMexception is not considered for now. Do you think this is a
reasonable approach to go forward with?

If I understand correctly, the issue is the behaviour of a method has
changed significantly.

If not implemented in PHP 8, where BC breaks are expected, when would be a
better time?

Would deviating and implementing the new behaviour with a different method
name e.g. appendAndAdoptChild(); or guarded by a version flag (so users
choose whether they want the 'Living' behaviour or the 'Level 2' behaviour
in this method) be options?

Peter

3 years ago by Benjamin Eberlei — view source

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On Mon, Sep 16, 2019 at 10:01 AM Peter Bowyer phpmailinglists@gmail.com
wrote:

Hi Benjamin,

I like the proposal.

On Mon, 16 Sep 2019 at 01:40, Benjamin Eberlei kontakt@beberlei.de
wrote:

I am asking about feedback especially on the section "Implementation
Details", that explains some key differences to "PHPify" the DOM Living
Standard API to PHP and ext/dom. Do you have any comments about the
reasonability of the choices?

I don't have feedback, other than to ask what choices other languages have
made when bringing in the DOM Living Standard API?

good question! the only other non javascript languages that have ext/dom
equivalents (i found) are java and python and both haven't changed their
APIs to the new living standard yet.

Also the section on "Not adopting Nodes for now" is new and I need some
feedback on this issue: To keep the proposal slim with respect to changing
existing behavior, the improved behavior of the DOM Living Standard over
Level 1-2 tof automatically adopting nodes instead of throwing a WRONG
DOCUMENT DOMexception is not considered for now. Do you think this is a
reasonable approach to go forward with?

If I understand correctly, the issue is the behaviour of a method has
changed significantly.

No, actually it behaves mostly the same. It only added a new use case that
previously lead to an exception, when you appendChild a node from a
different document. Since this is not really a line of code that happens
dynamically, this code will not be in the wild, instead you will find the
workaround
$element->appendChild($element->ownerDocument->importNode($otherNode));
which will not be affected by the new behvavior at all.

If not implemented in PHP 8, where BC breaks are expected, when would be a
better time?

This is no BC break in my opinion. Changing an exception that essentially
says "don't do this, you connected the wrong things" into the behavior that
people would expect anyways is not a BC break in my opinion and therefore
could be done at any time.

Would deviating and implementing the new behaviour with a different method
name e.g. appendAndAdoptChild(); or guarded by a version flag (so users
choose whether they want the 'Living' behaviour or the 'Level 2' behaviour
in this method) be options?

Peter

3 years ago by Benjamin Eberlei — view source

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On Fri, Mar 22, 2019 at 9:14 PM Benjamin Eberlei kontakt@beberlei.de
wrote:

Hi Internals,

Thomas and I are working on updating the ext/dom to add support for the
current DOM Living Standard API as standardized here:
https://dom.spec.whatwg.org/

https://wiki.php.net/rfc/dom_living_standard_api

This RFC is targeting 7.4 and contains three independent changes:

a set of new methods and interfaces that can be implemented BC as
addition to the existing ext/dom.

a removal of a few "dead" classes that are exposed to userland, but
neither documented nor containing implementation code.

a compatibility layer to switch the implementation between DOM Level 1-3
and the Living Standard in places where BC is not possible.

A pull request includes a nearly complete implementation of the new
methods, but nothing of the cleanup/compatibility yet:
https://github.com/beberlei/php-src/pull/1

We are looking forward for your feedback.

greetings
Benjamin

Heads up, I will start the vote on this RFC on Monday.

Given ext/dom argsinfo stub patch is finally merged I could add support for
arginfo stubs for this RFC as well, so there is only one refactoring task
open to reduce code duplication, which I will do after RFC acceptance.

Based on feedback here and private mails the RFC now only contains a single
change, the addition of new methods and interfaces from the current DOM
standard that can be added with minimal BC breaks.

4 years ago by Claude Pache — view source

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Beware that behaviour of some methods should differ between HTML and non-HTML documents. For instance, the RFC says:

DOMElement→nodeName casing was previously undefined, it is now changed to always uppercase.

However, the DOM Living Standard says it is uppercase (even, ASCII-uppercased) only in the HTML namespace. For XML documents, the casing is not modified.

—Claude

4 years ago by Benjamin Eberlei — view source

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On Fri, Mar 22, 2019 at 11:26 PM Claude Pache claude.pache@gmail.com
wrote:

Beware that behaviour of some methods should differ between HTML and
non-HTML documents. For instance, the RFC says:

DOMElement→nodeName casing was previously undefined, it is now changed
to always uppercase.

However, the DOM Living Standard says it is uppercase (even,
ASCII-uppercased) only in the HTML namespace. For XML documents, the casing
is not modified.

You are absolutely right, i missed that in the convoluted description of
the behavior :-) I need to rethink how this would fit with the
compatibility flags, it might cause a problem given that loadHTML for
example doesn't automatically put the elements into HTML namespace. I
updated the RFC to reflect this.

To be honest, the compatibility thing is what i am least sure in,
especially if this should be combined with the new methods + removal of
unused code or should be handled separately.

—Claude

4 years ago by Rob Richards — view source

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On Fri, Mar 22, 2019 at 11:26 PM Claude Pache claude.pache@gmail.com
wrote:

Beware that behaviour of some methods should differ between HTML and
non-HTML documents. For instance, the RFC says:

DOMElement→nodeName casing was previously undefined, it is now changed
to always uppercase.

However, the DOM Living Standard says it is uppercase (even,
ASCII-uppercased) only in the HTML namespace. For XML documents, the casing
is not modified.

You are absolutely right, i missed that in the convoluted description of
the behavior :-) I need to rethink how this would fit with the
compatibility flags, it might cause a problem given that loadHTML for
example doesn't automatically put the elements into HTML namespace. I
updated the RFC to reflect this.

To be honest, the compatibility thing is what i am least sure in,
especially if this should be combined with the new methods + removal of
unused code or should be handled separately.

—Claude

I'm still running through all the changes but my suggestion would be to
start with only new methods and then deal with the rest. At least with
the new functionality you don't cause any unintended BC breaks.

Rob

4 years ago by Benjamin Eberlei — view source

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On Thu, Mar 28, 2019 at 12:57 PM Rob Richards rrichards@cdatazone.org
wrote:

On Fri, Mar 22, 2019 at 11:26 PM Claude Pache claude.pache@gmail.com
wrote:

Beware that behaviour of some methods should differ between HTML and
non-HTML documents. For instance, the RFC says:

DOMElement→nodeName casing was previously undefined, it is now changed
to always uppercase.

However, the DOM Living Standard says it is uppercase (even,
ASCII-uppercased) only in the HTML namespace. For XML documents, the
casing
is not modified.

You are absolutely right, i missed that in the convoluted description of
the behavior :-) I need to rethink how this would fit with the
compatibility flags, it might cause a problem given that loadHTML for
example doesn't automatically put the elements into HTML namespace. I
updated the RFC to reflect this.

To be honest, the compatibility thing is what i am least sure in,
especially if this should be combined with the new methods + removal of
unused code or should be handled separately.

—Claude

I'm still running through all the changes but my suggestion would be to
start with only new methods and then deal with the rest. At least with
the new functionality you don't cause any unintended BC breaks.

Yes, thinking about this more I am coming to this conclusion myself :-) I
think the DOMImplementation and compatibility layer changes should probably
not be part of this RFC, it should only be about adding the new
functionality.

However, we will break BC anyways I realized with the registerNodeClass, if
you provide a subclass for DOMElement that implements
next/previousElementSibling (for example) with a __get overwrite, then this
RFC adding this method potentially with a slightly different behavior will
cause a BC break for users subclassing via registerNodeClass.

Rob