Re: Web IDL sequenceT and item() method
On 2011-12-11 13:55, Marcos Caceres wrote: On Fri, 09 Dec 2011 19:51:48 +0100, Glenn Adamsgl...@skynav.com (mailto:gl...@skynav.com) wrote: If the answer is that no item() method is implied, then does the use of sequenceT in these newer specs entail dropping this method (with respect to prior DOM specs)? I'm also unsure as to the purpose of sequence in practice. Perhaps some examples of expected usage would help a bit? I use it in Selectors API for the refNodes parameter, which needs to accept any collection of nodes, whether it be a NodeList, Array, jQuery object or any other generic numerically indexed object. e.g. These should all work var list = document.getElementsByTagName(section) document.querySelectorAll(:scopeh1, list) document.querySelectorAll(:scopeh1, $(section)) // JQuery $() document.querySelectorAll(:scopeh1, [elm1, elm2, elm3]) -- Lachlan Hunt - Opera Software http://lachy.id.au/ http://www.opera.com/
Re: Web IDL sequenceT and item() method
On Fri, 09 Dec 2011 19:51:48 +0100, Glenn Adams gl...@skynav.com wrote: If the answer is that no item() method is implied, then does the use of sequenceT in these newer specs entail dropping this method (with respect to prior DOM specs)? The DOM specifications probably need to move back to using interface rather than sequence. I was hoping sequence would define the whole collection thing magically, but it never turned out that way. Still not quite sure what the real use case is for sequence. -- Anne van Kesteren http://annevankesteren.nl/
Re: Web IDL sequenceT and item() method
On Sunday, 11 December 2011 at 12:21, Anne van Kesteren wrote: On Fri, 09 Dec 2011 19:51:48 +0100, Glenn Adams gl...@skynav.com (mailto:gl...@skynav.com) wrote: If the answer is that no item() method is implied, then does the use of sequenceT in these newer specs entail dropping this method (with respect to prior DOM specs)? The DOM specifications probably need to move back to using interface rather than sequence. I was hoping sequence would define the whole collection thing magically, but it never turned out that way. Still not quite sure what the real use case is for sequence. I'm also unsure as to the purpose of sequence in practice. Perhaps some examples of expected usage would help a bit?
Re: Web IDL sequenceT and item() method
On 12/11/11 7:21 AM, Anne van Kesteren wrote: The DOM specifications probably need to move back to using interface rather than sequence. I was hoping sequence would define the whole collection thing magically, but it never turned out that way. Still not quite sure what the real use case is for sequence. Last I checked, defining an interface that takes an in parameter that can be a nodelist or JS Array of nodes needs to use sequence, no? Or am I confusing it with array again? -Boris
Re: Web IDL sequenceT and item() method
In DOM-4 WD, NodeList is now defined as an interface, and not using sequenceT. [1] [1] http://www.w3.org/TR/domcore/#interface-nodelist From what I can tell, WebIDL sequenceT does not entail providing an item() method, which effectively makes it unusable for any of the pre-existing DOM interfaces with ECMAScript bindings. It may be worth modifying WebIDL to generate an item() method in its ECMAScript binding. On Sun, Dec 11, 2011 at 8:21 AM, Boris Zbarsky bzbar...@mit.edu wrote: On 12/11/11 7:21 AM, Anne van Kesteren wrote: The DOM specifications probably need to move back to using interface rather than sequence. I was hoping sequence would define the whole collection thing magically, but it never turned out that way. Still not quite sure what the real use case is for sequence. Last I checked, defining an interface that takes an in parameter that can be a nodelist or JS Array of nodes needs to use sequence, no? Or am I confusing it with array again? -Boris
Re: Web IDL sequenceT and item() method
On 11/12/11 11:55 PM, Marcos Caceres wrote:
I'm also unsure as to the purpose of sequence in practice. Perhaps some
examples of expected usage would help a bit?
Sequences are for pass by value lists of values. As with the array
type, they allow you to pass in a JS array to an operation:
interface A {
void f(sequencefloat xs);
};
getA().f([10, 20, 30]);
or indeed anything that feels enough like an array:
var o = { length: 3 };
o[0] = 10;
o[1] = 20;
o[2] = 30;
getA().f(o);
When used as an operation return type, a new JS array is created:
interface B {
sequencefloat f();
};
var a = getB().f();
assert(a instanceof Array);
var b = getB().f();
assert(a != b);
The array type T[] is used for array-like objects for which references
can be kept by platform objects or by user script, and possibly modified
by either of them.
If we were ever going to extend one of the built in types with item(),
it would be the array type T[], which corresponds to a platform object
that looks a bit like a JS array but is different in various ways (extra
prototype object in the chain, non-sparse, can be read only / fixed length).
To get an object that is like a T[] but with other custom members, you
currently have to use [ArrayClass] on an interface:
[ArrayClass]
interface FixedLengthWritableNodeList {
readonly attribute unsigned long length;
getter Node item(unsigned long index);
setter void (unsigned long index, Node value);
};
All [ArrayClass] means is that
Object.getPrototypeOf(FixedLengthWritableNodeList.prototype) will be
Array.prototype instead of Object.prototype. So you can see you need to
hook up the length and getters/setters yourself there.
Re: Web IDL sequenceT and item() method
On 12/12/11 2:21 AM, Boris Zbarsky wrote: Last I checked, defining an interface that takes an in parameter that can be a nodelist or JS Array of nodes needs to use sequence, no? Or am I confusing it with array again? The confusing thing is probably that for the case where you want to take in an array as a parameter, and the receiving object will not modify the array or keep a hold of it, both sequenceT and T[] will work.
Web IDL sequenceT and item() method
Hi Cameron, Does the ECMAScript binding for the IDL sequenceT type imply the existence of an item() method as a element accessor, where an element is a property whose property name is an array index? If so, then could describe how it is implied? The reason I ask is because I'm wondering about compatibility with earlier DOM specs, e.g., NodeList, CSSRuleList, etc., where an explicit item() method is defined, and which, in recent newer specifications based on Web IDL, has been re-expressed in terms of sequenceT. In my review of ECMA 262 3rd and 5th editions, I don't see an explicit mention of an item() method on Array objects (or their prototype), which are the ECMAScript binding for IDL sequenceT. If the answer is that no item() method is implied, then does the use of sequenceT in these newer specs entail dropping this method (with respect to prior DOM specs)? Regards, Glenn
