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RE: algorithmic normative conformance requirements, design principles, etc.

From: Ian Hickson <ian@hixie.ch>
Date: Thu, 28 May 2009 08:42:17 +0000 (UTC)
To: Larry Masinter <masinter@adobe.com>
Cc: HTML WG <public-html@w3.org>
Message-ID: <Pine.LNX.4.62.0905280840111.10857@hixie.dreamhostps.com>
On Wed, 27 May 2009, Larry Masinter wrote:
> But in fact there is no way to determine if image.width and image.height 
> are simultaneously available, because 'available' is dynamic. Any 
> program of the form
>   if (image.width != 0) { ... something using image.height ...
>                           which assumes image.height is non-zero ...}
> will not always function properly, if the image becomes unavailable 
> between the time image.width is computed and when image.height is 
> accessed, because images can become "unavailable", because of network 
> congestion, server timeout, delay, etc.

As noted in my earlier e-mail, this is in fact not possible due to the use 
of the event loop mechanism.

> My original point was that this was an instance of using algorithmic 
> specification rather than using language constraint specification.

How would you phrase it using constraints? I tried, but couldn't work out 
how to do it in a way that was actually equivalent in terms of having the 
same effective normative conformance criteria.

> Perhaps you'd like to find some part of the spec which *isn't* ambiguous 
> or poorly specified in this way?

It's not clear what ambiguity you believe exists here. Could you 
elaborate? If there is something ambiguous I definitely want to fix it.

> Some single example / page / section which you think is completely 
> specified both from a user and client point of view?

As far as I can tell, this (image.height/image.width) is such a case.

Ian Hickson               U+1047E                )\._.,--....,'``.    fL
http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
Things that are impossible just take longer.   `._.-(,_..'--(,_..'`-.;.'
Received on Thursday, 28 May 2009 08:42:51 UTC

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