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Re: Constructible Exceptions

From: Marcos Caceres <w3c@marcosc.com>
Date: Sun, 25 Mar 2012 17:03:37 +0100
To: Cameron McCormack <cam@mcc.id.au>
Cc: public-script-coord <public-script-coord@w3.org>
Message-ID: <B098F1D383DB47C682F5260038ABBCB0@marcosc.com>



On Sunday, 25 March 2012 at 03:16, Cameron McCormack wrote:

> Marcos Caceres:
> > Right. But it's as close as I can get to the real thing… so again we
> > come full circle about having some means of create a DOMException (or
> > if faking it is good enough, which may just be).
>  
>  
> Currently the requirements for platform exception objects are the same  
> as for other platform objects. You can't for example create a Node  
> object yourself in JS and have it work with the browser's DOM  
> implementation.  

Right. Without getting too academic here, that kinda sucks as an "interface" is not really an "interface" (in the classical black-box sense); this split in the platform between Platform objects and other objects kinda sucks… but such is life. Hopefully something we can address in the future.  

> Good enough for what is the question, I guess. Given  
> DOMException is defined like
>  
> exception DOMException {
> // ...
> short code;
> };
>  
> you cannot create a JS object with say  
> Object.create(DOMException.prototype) and be able to access the code  
> property on it, because the getter and setter functions will be defined  
> to check if the object they're called on is a real platform exception  
> object of type DOMException. So accessing that property will throw a  
> TypeError instead.

Yep. I guess the use case I had in mind would enter into the platform (as everything is interpreted as within user objects… it's mostly for prototyping things like this: http://specs.wacapps.net/accelerometer/implementation/Accelerometer.js).  
    
> Also Object.prototype.toString.call(yourObject) will return "[object  
> Object]" instead of "[object DOMException]".
>  
> So I think we really browsers to implement the [Constructor] here. :)
Agreed… grumble:) Thanks for the clarifications!    

I got this far based on our discussions:  
http://jsfiddle.net/yDNgL/31/

Added it to this:
http://stackoverflow.com/questions/5136727/manually-artificially-throwing-a-domexception-with-javascript
Received on Sunday, 25 March 2012 16:04:12 UTC

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