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Re: [css-variables] How to spec the OM for vars?

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Thu, 23 Aug 2012 18:12:55 -0700
Message-ID: <5036D517.7040403@mit.edu>
To: www-style@w3.org
On 8/23/12 5:46 PM, Tab Atkins Jr. wrote:
> How can we do this in WebIDL?

You can declare getters and setters that would live directly on the 
object in WebIDL to support open-ended sets of properties.  So basically 
something like this:

   getter DOMString (DOMString varName);
   setter void (DOMString varName, DOMString varValue);

Then your prose says that the set of supported property names is 
whatever that set is (e.g. for non-computed style it's variables that 
are in that declaration, I assume; for computed style it's whatever you 
define it to) and defines what the behavior of the getter and setter is 
for a given supported property name.

If you want to allow creation of variables via this API, not just 
setting of existing ones, then you would change the second line above to:

   setter creator void (DOMString varName, DOMString varValue);

If you also want to allow deletion of variables, you would add:

   deleter void (DOMString varName);

Two caveats:

1)  The interaction with web content that sets expandos on CSS 
declarations might be interesting.  Let's hope there's not too much of it.

2)  Using a getter and setter as above will not allow variable names to 
shadow properties on the proto chain.  So if you have a variable named 
getProperty, doing style.getProperty will still get you the function off 
the prototype.  And if you have a variable named "display", then 
style.display will still be the display property value, not the value of 
the variable.  I think this is in fact the behavior we want here.

-Boris
Received on Friday, 24 August 2012 01:13:29 GMT

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