[webkit-dev] Adding ENABLE_FLEXBOX to WebCore

[Maciej Stachowiak]

On Jun 9, 2011, at 3:00 PM, Tony Chang wrote:

> On Thu, Jun 9, 2011 at 1:19 PM, Sam Weinig <weinig at apple.com> wrote:
> Why should we implement this spec? We already have one flex box implementation that we can never remove (and corresponds closely to Firefox's) so it seems to me that we should work on standardizing that model. Adding a large bunch of code that duplicates existing functionality seems foolish.
> 
> There was an attempt to standardize the old flexbox (http://www.w3.org/TR/2009/WD-css3-flexbox-20090723/), but that effort seems to have fizzled.  I attempted to write some patches to make WebKit's old flexbox implementation match that spec, but Hyatt recommended against that because it can only break sites that are targetting WebKit's existing flexbox implementation.  WebKit's implementation and Firefox's implementation are different enough that the current uses of flexbox are mostly browser specific (e.g., dashboard widgets).
> 
> If the issue is the syntax for describing flexing, perhaps the spec should be written in a backwards compatible way, that supports both the new syntax and the old syntax, but the underlying implementation can remain.
> 
> The new syntax describes a superset of features provided by the old syntax.  I think it's possible to implement the old flexbox on top of the new flexbox implementation and that seems like a worthwhile goal, but it'll probably easier to see the similarities for refactoring after the code has been written.

If it's a superset then I would much prefer to see the old code incrementally enhanced to support the extended features and new syntax, then to first rewrite from scratch and merge. Maybe the right step 1 is refactoring and cleaning up the old code. Rewriting from scratch throws away accumulated knowledge, and in cases where we have to keep the old implementation too, bloats the code.

Regards,
Maciej

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