RE: Proposed CR change to default bidi behavior for elements with dir

As I've heard a number of statements of support (in person) and no objections, I have folded this change into the CR branch [1]. 

Please note: since the time I posted the initial spec change for review [2], Ian has produced a more comprehensive change [3] that updates some descriptions I had missed and that changes <bdo dir="ltr|rtl"> to be directionally isolated (to be unicode-bidi: isolate-override instead of unicode-bidi: bidi-override), as further requested by the i18n WG [4]. This keeps the behavior of dir consistent across different elements and enhances the usability of bdo under common usage. It is this later change (from the WHATWG spec) that I have chosen to fold into CR (as well as override my original change in the HTML5.1 master branch).

Please reply back with any comments or issues.

Thanks,
Erika 

[1] https://github.com/w3c/html/commit/ca1986c79c26e49f7781577021b090df159c4c7a 
[2] https://github.com/w3c/html/commit/efbf692e44fa3e6b9d66a0823fc2133ff1d18f1e 
[3] https://github.com/w3c/html/commit/cf3f3dbbc3a28e0b6f82d6395427c84b4bf489a8 
[4] https://www.w3.org/Bugs/Public/show_bug.cgi?id=23260#c17 

-----Original Message-----
From: Erika Doyle Navara [mailto:Erika.Doyle@microsoft.com] 
Sent: Thursday, October 24, 2013 4:34 PM
To: 'public-html@w3.org'; member-i18n-core@w3.org; Richard Ishida; Addison Phillips; Sam Ruby (rubys@intertwingly.net) (rubys@intertwingly.net); Paul Cotton
Subject: Proposed CR change to default bidi behavior for elements with dir

The I18N working group has requested [1] that bug 22326 [2] be addressed in the HTML5 CR timeframe. This bug represents the implementation of the I18N proposal [3] to change the bidi semantics of the dir attribute to imply isolation rather than embedding. 
 
The technical discussion so far has taken place on the WHATWG cloned bug [4], but here is a summary of the pro/con arguments (Richard/I18N members, please correct if I have missed or misrepresented anything):

Pro (make dir="" imply unicode-bidi:isolate) ==========================================
- HTML5 is consistent with  Unicode 6.3 spec (and other specs, like CSS3 Writing Modes) in making isolation the default for all inline bidi text embeddings

- Bidirectional text is easy and intuitive for web developers to implement correctly, and without needing to know anything about the intricacies of bidi algorithm

- Drives browser implementation to make the web less buggy with bidi issues. Problems with existing legacy pages will be fixed automatically.

- Easy transition period while browsers adopt new behavior (code will work better in browsers with the change, but work the same in browsers without)

- Once a browser supports isolation, it is trivial to implement this change in semantics for dir (simple change to default style sheet)

Con (dir="" continues to imply unicode-bidi:embed) ===========================================
- Currently no implementations yet of this behavior

Rebuttal: IE8-IE10 did a similar (but not identical) change, however, and there was little or no compat fallout, both according to IE bug records and also i18n community

- Default isolation for dir potentially makes the new HTML5 <bdi> element seem redundant.

Rebuttal: <bdi> element is still useful in cases when text of unknown direction is dynamically inserted to a page (because it has new HTML5 dir="auto" value as default, which determines dir at run time). Perhaps we could even re-label <bdi> from "bidi isolate" to "bidi insert".

...given the favorable reasons outweighing the unfavorable, I have implemented this change in the HTML5.1 Nightly draft, and believe it merits porting over to the HTML5 CR draft as well:

	https://github.com/w3c/html/commit/efbf692e44fa3e6b9d66a0823fc2133ff1d18f1e 

Please reply with any objections. Otherwise, I will port this change to the CR draft within a couple weeks (11/6).

Thank you,
Erika

[1] http://lists.w3.org/Archives/Public/public-html-admin/2013Oct/0015.html
[2] https://www.w3.org/Bugs/Public/show_bug.cgi?id=22326
[3] http://www.w3.org/International/wiki/Html-bidi-isolation#Proposal_A:_change_the_dir_semantics
[4] https://www.w3.org/Bugs/Public/show_bug.cgi?id=23260

Received on Tuesday, 26 November 2013 00:42:01 UTC