- From: David Woolley <david@djwhome.demon.co.uk>
- Date: Fri, 13 Jul 2001 23:21:10 +0100 (BST)
- 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 fundamental. > 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