Thomas, Well, even if the knowledge I was seeking to clean my code up isn't
possible in the language, at least now I know how it works.
I've researched apply and call following your prompt and I think I finally
understand how some of the 'this' magic in prototype works.
I've looked at the argument stuff previously and never had the time to
deconstruct it and actually understand it - I couldn't see how bind actually
did it's magic.
I really appreciate your help, even if it was leaning towards vampire
teritory.
Gregory, the specific constructor I wanted to use apply on was a date
object.
I have an array with [year,month,day,hour,min,sec] and wanted to create a
date object from it.
an example is
var d = new Date(2007,09,09,12,36,34);
I wanted to replace the numbers with my 6 element array.. I'm aware I can go
ar[0],ar[1] etc but that's not as elegant so I was looking to improve the
syntax.
Gareth
On 11/30/07, Gregory Seidman <[EMAIL PROTECTED]> wrote:
>
>
> On Thu, Nov 29, 2007 at 04:00:26AM -0800, Tobie Langel wrote:
> > Unfortunately, JavaScript doesn't let you use apply on constructors.
> > You're out of luck on that one.
>
> Correction: JavaScript doesn't let you use apply on constructors *easily*.
>
> var MyClass = Class.create({
> initialize: function(num1, num2, num3) { /* do stuff */ }
> });
>
> var myargs = [ 1, 2, 3 ];
> var foo = {};
> foo.__proto__ = MyClass.prototype;
> MyClass.apply(foo, myargs);
>
> Note that the order of those last two lines is very important. I think
> that
> with Prototype classes (i.e. those created with Class.create), you can
> sort
> of skip a step:
>
> var foo = {};
> foo.__proto__ = MyClass.prototype;
> foo.initialize.apply(foo, myargs);
>
> Note that this is based on slides from Dan Webb and that I have not
> actually tested it.
>
> I might argue that the function returned by Class.create() should not only
> call initialize but should first set this.__proto__ to
> arguments.callee.prototype, making this sort of thing even simpler. Does
> this sound appealing to anyone? It's a one-line patch.
>
> > Best,
> > Tobie
> --Greg
>
> > On Nov 29, 11:20 am, "Gareth Evans" <[EMAIL PROTECTED]> wrote:
> > > Well, I tried google and it was proving to be difficult cos all I
> turned up
> > > was articles on passing arrays to functions.. and I was pretty sure it
> was
> > > done in prototype so I figured it was a good place to ask.
> > >
> > > I like that term, help vampire :)
> > >
> > > I was trying to apply on the Date constructor though, and the parser
> didnt
> > > seem to like me (the script just stopped executing on that line), so I
> will
> > > play around a bit more and see if I did something dumb or if I need to
> add
> > > an extra set of brackets or something..
> > > It's quite good to have a mailing list such as this which the
> occasional
> > > idea can be bounced off other members...
> > >
> > > I know it's mostly prototype related but I have noticed an upturn in
> overall
> > > questions recently..
> > >
> > > Google is usually my first port of call anyway, followed by asking
> people :)
> > >
> > > Gareth
> > >
> > > On 11/29/07, Thomas Fuchs <[EMAIL PROTECTED]> wrote:
> > >
> > >
> > >
> > > > Slacker! I guess others will profit as well from this info. But
> don't
> > > > you become a Help Vampire[1]. ;)
> > >
> > > > - Thomas
> > > > [1]http://www.slash7.com/articles/2006/12/22/vampires
> > >
> > > > Am 29.11.2007 um 09:22 schrieb Gareth Evans:
> > >
> > > > > Thanks Thomas, I thought it was used in prototype but a lot of the
> > > > > argument stuff I don't follow. It was quicker to ask :)
> > >
> > > > > Gareth
> > >
> > > > > On Nov 29, 2007 9:21 PM, Thomas Fuchs < [EMAIL PROTECTED]> wrote:
> > >
> > > > > You want Function#apply.
> > >
> > > > > see
> > > >
> http://developer.mozilla.org/en/docs/Core_JavaScript_1.5_Reference:Gl...
> > >
> > > > > Best,
> > > > > Thomas
> > >
> > > > > Am 29.11.2007 um 07:39 schrieb Gareth Evans:
> > >
> > > > > > Hey Guys
> > >
> > > > > > Does anyone know if I have an array if I can pass that array to
> a
> > > > > > function, *as* the parameters.. not pass it as a parameter, but
> > > > > > effectively have my scoped array become function.arguments .
> > > > > > I have a regular expression that splits an ISO date string
> that's
> > > > > > given me a match array, which I then split to drop the first
> match
> > > > > > (the whole string) leaving me with year,month,day,hour,min,sec
> and I
> > > > > > want to pass that to new Date()
> > > > > > I could go var d = new Date(ma[0],ma[1],ma[2]... but I figure if
> I
> > > > > > can do the arguments thing then its a technique i could adopt
> > > > > > elsewhere.
> > > > > > I control both sides of the interface, the source as well as the
> > > > > > processing so I know the format will always be the same.
> > > > > > (incidentally, the date comes from a .net date originally, and I
> use
> > > > > > a .tostring("s") to get the iso format, which is passed to json
> as a
> > > > > > string - there may be a better way for that)
> > >
> > > > > > Hope this makes sense,
> > >
> > > > > > Gareth
> > >
> >
>
> >
>
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