Prev: Do not assign undefined to window event handlers in IE/MSHTML
Next: Komodo Edit: Editor settings?
From: Dmitry A. Soshnikov on 30 Apr 2010 03:35
On Apr 29, 11:45 pm, Ry Nohryb <jo...(a)jorgechamorro.com> wrote:

>
> > "in contrast with non-standard __proto__ extension of some ES3
> > implementations"
>
> If it's non-standard it's not "in contrast" with ES5...

So, how to form this sentence better? With keeping the same sense.

Dmitry.
From: Dmitry A. Soshnikov on 30 Apr 2010 04:28
On Apr 30, 12:19 am, Ry Nohryb <jo...(a)jorgechamorro.com> wrote:
> On Apr 29, 8:50 pm, "Dmitry A. Soshnikov" <dmitry.soshni...(a)gmail.com>
> wrote:
>
>
>
> > On Apr 29, 5:46 pm, Ry Nohryb <jo...(a)jorgechamorro.com> wrote:
>
> > > On Apr 29, 2:08 pm, "Dmitry A. Soshnikov" <dmitry.soshni...(a)gmail.com>
> > > wrote:
>
> > > > On Apr 29, 3:33 pm, Ry Nohryb <jo...(a)jorgechamorro.com> wrote:
> > > > (... ) And forgot about that only objects with
> > > > "Array" [[Class]] has overloaded internal methods related to arrays
> > > > stuff (15.4.5.1 in ES5).
>
> > > Yeah. Object.create() returns an {}. To subclass [] we'd need an
> > > Array.create(). I told this once to Brendan Eich @ es-discus, but
> > > unfortunately I couldn't understand his too-complicated-for-me
> > > response... :-)
>
> > >https://mail.mozilla.org/pipermail/es-discuss/2009-December/010425.html
>
> > Yep, I see.
>
> > And Brendan suggested [[Put]] to be delegable, but not determinate
> > only by some invariants (as it is now, and will), e.g. by [[Class]].
> > If [[Put]] would be delegable, then: own a.[[Put]] -> not found -> a.
> > [[Prototype]].[[Put]] - found and set "length" property accordingly.
>
> > In addition (as a variant) could be ability only to specify a
> > [[Class]] (it could be named as "type" e.g.) of the created object:
>
> > Object.created({
> >   prototype: Array.prototype,
> >   type: "Array",
> >   // other properties
>
> > });
>
> > But it will be "too hard" (because require to be "prototype" and
> > "type" in this case a special properties, but not just normal). Also,
> > as I heard recently committee doesn't like (and won't standardize)
> > double-side-double-underscored __special__ properties, borrowed to ES
> > from Python. As actually __proto__, which is direct analogy of the
> > Python's __class__ and is for the same purpose.
>
> > Also, as was recently discussed @es-discuss list, all that new methods
> > which is now directly in "Object" constructor, but not in
> > "Object.prototype" led to that now we have three (!) syntactically
> > different approaches for the _same_ semantically entity - using
> > methods related with objects. The only reasonable thing is
> > stratification methods on "Meta" and "App" levels. But it is also very
> > debatable what should be treated as a "meta" and what is not (and
> > should ES do this the way as Java does). If will be interesting,
> > here's the complete discussion: <URL:https://mail.mozilla.org/pipermail/es-discuss/2010-April/010908.html>
>
> Yeah. I had seen that already.
>
>
>
> > I already mentioned:
>
> > var o = Object.freeze(
> >    Object.seel(
> >      Object.defineProperties(
> >        Object.create(proto),
> >        properties
> >      )
> >    )
> > );
>
> > And:
>
> > var o = Object.create(proto)
> >    .defineProperties(properties)
> >    .seel()
> >    .freeze();
>
> > that it is obvious that the first source even harder to read. And this
> > forced indention and repetition of Object.-Object.-Object. is just
> > ugly.
>
> But that's a no-problem. They way they've done it you can build that
> syntax yourself, if you wish:
>
> (function (op) {
>   op.create= function (proto, p) {
>     return Object.create(proto, p ? p : undefined); };
>   op.defineProperties= function (p) {
>     Object.defineProperties(this, p); return this; };
>   op.seal= function () { Object.seal(this); return this; };
>   op.freeze= function () { Object.freeze(this); return this; };
>
> })(Object.prototype);
>
> var o=
> ({}).create(proto).defineProperties(properties).seal().freeze();
>
>

Yup, I also already showed m quickly solution for that (with aliases
for new methods (with renaming some of them) and some additional
useful "sugar"): http://gist.github.com/367080/ .

Brendan himself pointed one of the reasons of why that methods are
directly in constructors (on examples with "array extras"), but not in
prototypes because -- comparing it with how Python's methods are
reflected. But he (at the same time) don't mention that in contrast
with JS, Python's properties/methods resolution chain is:

obj -> obj.__class__ -> ...

and in JS is:

obj -> obj.__proto__ -> ...

meanwhile constructor function after its main purpose (creating of
this object) isn't related with the "obj" at all.

In other words, in Python syntactic construction obj.method() is just
a "sugar" which automatically transforms to ObjClass.method(foo). But
in JS we should make aliases in two places - in constructor itself and
in the prototype - to make it convenient from the code reuse viewpoint
and at the same time having this methods generic, e.g. independent
from the [[Class]] of "this" value.

So, making aliases for all new "Object." methods seems to me
completely OK. At least, as I mention, I'll do it in all my own
projects.

Of course, from the other hand, it is "pain" if project uses several
3rd-party libs. Then it (being justified by committee and Brendan -
i.e. "avoid naming collisions and not to break the Web") should have
overloaded code always mentioning a long "namespace" before the needed
property/method. Yeah, that at the same time that now "with" is so
"evil" that should throw an exemption in "strict". Although, "with"
was (in correct using) is just a good analogy for "using namespace"
e.g.:

namespace("My.Widget")(function () { with (My.Widget) {

updateTree().repaint();

}});

Of course it's just an example (and maybe have some lacks), but -
nevertheless. To be fair, I myself do not use/used "with" on practice,
but think that there's nothing "evil" in it and taking into account
some circumstance I suppose, that I _could_ use it (yeah, function
expressions will have it scope chain, but, that's another question).

But, I guess all this is already another topic.

>
> > The same could be for:
>
> > var o = Object.create(SomePrototypeObject, {
> >   ...
>
> > });
>
> > And:
>
> > var o = {
> >   __proto__: SomePrototypeObject,
> >   ...
>
> > };
>
> > The second source seems lighter, but, repeat, the committee doesn't
> > like __special__ properties. But, everything can be changed.
>
> I don't think so. __proto__ is not a Good Thing™ due to some obscure
> security reasons, and many of the seemingly odd-looking decisions wrt.
> the new API, too, I heard.

Yeah, maybe (and concerning to web, I guess; else, Python is also just
a "big security hole"?), but from the code reuse viewpoint, it is (in
my opinion) more clear and elegant. Also, declarative definition style
also is more elegant.

Dmitry.
From: Dr J R Stockton on 30 Apr 2010 16:40
In comp.lang.javascript message <f8544770-3eab-4a85-ac2f-3116c138e5c7(a)z3
0g2000yqz.googlegroups.com>, Thu, 29 Apr 2010 02:27:10, Dmitry A.
Soshnikov <dmitry.soshnikov(a)gmail.com> posted:
>OK, the new series has just begun.
>
>"ECMA-262-5 in detail. Chapter 1. Properties and Property
>Descriptors."
>
>http://dmitrysoshnikov.com/ecmascript/es5-chapter-1-properties-and-
>property-descriptors/
>
>It isn't already a translation, but the original. But, nevertheless,
>additions/corrections -- technical and in English are welcome.

Web http://validator.w3.org/ does not much like the page.

The CSS file includes :-

body {
background-color: #F9F9F9;/*#F1F3E9;*/
font: 12px Verdana, Arial, 'Helvetica', sans-serif;
padding: 0;
}


Fixing the font size is bad; leave it at 100% of reader's preference.
Verdana is not good, because it is "big for its size" and if it is
present in your system and absent on a reader's system the reader will
be shown a smaller-looking font.

Try removing everything not needed from the CSS; make all text sizes
percentages, and give other text-related sizes in ex or em units.

code ... "font: 9pt monospace, Verdana, Arial, 'Helvetica', sans-serif;"
- is it not the case that all systems have monospace, as it is generic?


If writing one's own set of pages, I suggest that one should never use a
CSS file from "outside". Write a new one, and copy into it only what
one knows, and proves, is good. And validate it.


On font size : I have here two networked PCs, and the screen sizes are
almost identical in inches (and presumably in centimetres). But the
desktop one has a 1280*1024 CRT screen, and the laptop has a 1024*768
LCD screen, naturally with sharper pixels. Your font size is noticeably
better on the laptop.

--
(c) John Stockton, nr London, UK. ?@merlyn.demon.co.uk Turnpike v6.05 IE 7.
Web <URL:http://www.merlyn.demon.co.uk/> - FAQish topics, acronyms, & links.
MiniTrue is good for viewing/searching/altering files, at a DOS / CMD prompt;
free, DOS/Win/UNIX, new via <URL:http://www.merlyn.demon.co.uk/pc-links.htm>.
First  |  Prev  | 
Pages: 1 2 3
Prev: Do not assign undefined to window event handlers in IE/MSHTML
Next: Komodo Edit: Editor settings?