On Tuesday, 2011-11-15 at 10:58 , David Flanagan wrote:
> On 11/14/11 5:17 PM, Allen Wirfs-Brock wrote:
> > On Nov 14, 2011, at 4:50 PM, David Flanagan wrote:
> >
> > > On 11/14/11 4:16 PM, Allen Wirfs-Brock wrote:
> > > > On Nov 14, 2011, at 3:15 PM, David Flanagan wrote:
> > > > > I have a bad feeling about making 'new' work with both functions and
> > > > > object exemplars. If we can have two different types of classes,
> > > > > we're going to end up using typeof on our class objects to figure out
> > > > > what kind of class they are. If I've got a value C from a library and
> > > > > I think it is an object exemplar, but it is in fact a constructor
> > > > > function, then 'class C' is going to return Function rather than C
> > > > > itself...
> > > >
> > > > Well, new'ing object exemplars has always been the central concept of
> > > > our discussions about them. Essentially it is the self style of object
> > > > creation and arguably the way the prototypal instantiation is supposed
> > > > to work. It seems to be what people who really like prototypal
> > > > inheritance really want to do.
> > > >
> > >
> > > Apparently I wasn't paying attention to the early discussions about
> > > object exemplars. I've heard the term used, but missed the point about
> > > changing the behavior of new. It seems to me people who want to use
> > > self-style object creation can use Object.create() and people who want to
> > > use JavaScript-style object creation can use new like we've been doing
> > > for 15 years. (Just today I wrote a blog post explaining why I'm hoping
> > > for classes in ES.next, and included, as part of my argument, the
> > > assertion that all the proposals on the table are just syntax sugar
> > > without new language semantics. I was wrong about that, I guess!)
> > >
> >
> > Object create doesn't do the job because it doesn't provide for calling an
> > "initialize" methods (turns out to be a very important part of the
> > self-style).
> >
>
> Its not like there's a large community of self programmers out there who
> are migrating to JavaScript... It seems to me that if you like the
> object exemplar style, then you don't want to be using the new operator
> and constructor functions (or things that appear to be constructors
> because they're used with new). Instead you want to define factory
> functions that use Object.create():
>
But making it possible to reuse libraries that are written either object or
class exemplar supporters is a huge win to me!
>
> function Range(from, to) {
> return Object.create(Range.methods, {
> from: { value: from, enumerable: true },
> to: { value: from, enumerable: true}
> });
> }
> Range.methods = {
> includes: function(x) {
> return this.from <= x && x <= this.to;
> }
> };
> Range(1,3).includes(2); // => true
>
> > > Do JavaScript programmers want exemplars or do they want classes?
> > They seem to be split. Some vocally ask for better support for prototypal
> > inheritance other vocally ask for classes.
> >
>
> Irakli has self-identified in this thread as wanting object exemplars
> but he has also defined a simple and useful Class() function for working
> with them. I suspect that part of the appeal of object exemplars is
> that it is easier to write support functions like Class() for working
> with them. That is: we can make the proponents of object exemplars
> happy with good library support. But for classes, we need language
> support...
>
> > I think what everybody is asking for is a better way to "created named
> > object abstractions". The term exemplar is just one that I introduced into
> > the discussion to make it easier to talk about the different kinds of
> > entities you might apply such names to. In some language you name a "class
> > declaration", in others you name a prototypal instance, in JS you have
> > historically named a function. Exemplar was intended to be a generic for
> > such "named object abstractions". An object exemplar is a self style
> > prototype, a class exemplar is the sort of thing you find in languages llke
> > Java. A function exemplar is a JS constructor,
> Are there existing languages that support more than one kind of exemplar
> at the language level? It seems to me that JS is stuck with function
> exemplars, and we should work to make those better, not add complexity
> to the language by adding support for another style of exemplar.
>
> David
>
> _______________________________________________
> es-discuss mailing list
> es-discuss@mozilla.org (mailto:es-discuss@mozilla.org)
> https://mail.mozilla.org/listinfo/es-discuss
>
>
_______________________________________________
es-discuss mailing list
es-discuss@mozilla.org
https://mail.mozilla.org/listinfo/es-discuss
