On Tue, 5 Sep 2006, Henri Sivonen wrote:
On Sep 5, 2006, at 19:33, Dave Raggett wrote:
On Wed, 6 Sep 2006, Lachlan Hunt wrote:
Another key difference is that in WebForms 2.0 the data is owned
by the field, thus a field can state which forms it belongs to.
It is better software engineering for the field to act as a view
onto the data. Decoupling the view and the data makes it easier
to support structured data and to describe calculations for
derived fields and other purposes.
It is possible and even convenient to use JavaScript closures
attached to the DOM nodes of form fields for binding the form
fields with an XHR-load/saved data model document tree. Such an
arrangement has the benefit that it is backwards-compatible with
existing Web browsers (including IE6).
But why go to such difficulties when a declarative solution is
achievable? A cross platform JavaScript libarary can provide
support for existing browsers, enabling authors to focus on
declarative markup rather than scripting. Also from what I hear,
many developers are having trouble with Ajax and XHR.
If the expression evaluates to false, the field is considered to
be invalid. I got the name wrong and it should have been called
validate. The expression could act over just the field's value,
but it could also refer to the values of other fields. It could
even call out to a function defined as part of a web page script.
What is the advantage over calling a JavaScript function from the
onchange handler?
http://whatwg.org/specs/web-forms/current-work/#setcustomvalidity
If you are good at maintaining custom JavaScript, then perhaps the
benefit is less valuable to you, but a simple expression will be
easier to check for others.
WF2 essentially limits to boolean literals, and you cannot
describe the conditions under which a field is required. For
example, your parent's name might be required if your age is
under 15.
The onchange handler of the age field can invoke a JavaScript
function that toggles the required attribute on the name of parent
field.
Sure, a Turing complete procedural solution is indeed very powerful,
but that's the point. A more constrained approach is easier to
verify against the application requirements.
The WF2 output element uses a JavaScript expression to evaluate
to a string. What benefit does an XPath expression provide
It is more declarative than calling out to a JavaScript function.
Why is that a benefit?
Same as above. I guess I won't be able to convince you of the
benefits of declarative representations.
Dave Raggett <[EMAIL PROTECTED]> W3C lead for multimodal interaction
http://www.w3.org/People/Raggett +44 1225 866240 (or 867351)
