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Re: Fw: Re: Web Access; When the Rubber Meets the Road

From: David Woolley <david@djwhome.demon.co.uk>
Date: Fri, 13 Jul 2001 23:21:10 +0100 (BST)
Message-Id: <200107132221.f6DMLAJ04467@djwhome.demon.co.uk>
To: w3c-wai-ig@w3.org
Cc: pdchapin@AMHERST.EDU
> From: "Paul Chapin" <pdchapin@AMHERST.EDU>

> and is why newspapers and magazines have been using columns for decades.
> But the accessibility of column text like this is highly problematic
> with
> low end software.

Also, setting complex columnar formats is a difficult problem, even
when font sizes and page widths are under your control.  I believe CSS3
has a simple, regular column format, but designers tend to want to have
much less regular shapes, or even do layouts with multiple boxes.  With
regular columns, you can trade off height to get the contents of the
columns balanced, but laying out multiple boxes without under or
overflowing the last box is difficult.

The only satisfactory way of doing complex columnar layout is with
a page description language, and doing the layout completely at the
authoring stage, but web designers try to do it by making unreasonable
assumptions about consistent font sizes, etc. (I gave up on one of these
last weekend!)  HTML is neither a page description language allowing the
layout to be done up font, nor are browsers top end desk top publishing
program that might be able to do a sensible layout client side.

Note, that, if it weren't for the fact that designers try to control
presentation on nearly all commonly accessed pages, the browser could
generate a multi-column display, so the issue with line length is not

> JavaScript for an example.  Can anybody come up with a case where a
> sufficiently intelligent piece of software would not be able to deal
> with a
> JavaScript and convert it into something useful?

I don't think there is any doubt that Javascript is a general programming
language, and therefore Turing complete.  That means that it can only 
be emulated by another general programming language.  For instance, there
is a fundamental theorem called the halting problem, that says that you
can write a program for such a mechanism that can only be proved to
eventually halt by running it until it actually halts.

You cannot cover what Javascript can do without using something equally
powerful.  That's even before you start considering the document and
browser object models, which are not Javascript, but which most people
mean when they say Javascript.  These rely fundamentally on changing the
document, and combined with the halting problem, may change it in 
infinite ways (although most scripts attempt not to do this!).

To convert scripted HTML to static form, you have to either recognize
common idioms, but these change with time, so you have a horrendous 
maintenance task, or you have to use artificial intelligence to work
out what the script is actually attempting to achieve.  Even then,
you may well need to add server side scripting to handle dynamic 
behaviour, or avoid lots of redundant entry of data.
Received on Friday, 13 July 2001 18:46:25 UTC

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