Re: [xml-dev] Evolution of a markup language: replace recurring patterns that are imperatively implemented with declarative solutions

>
> How has XML evolved? Can you cite examples of where usage patterns have been observed and then equivalent declarative solutions have been provided?
>

I don't think you can say XML itself has evolved since, by design,
there has only been one version in a decade. However, I think
a classic XML-related example of the progress from Javascript to
declarative markup has been the evolution from XML Data Islands
to XForms.

Regards

----
Stephen D Green



On 22 December 2010 14:50, Costello, Roger L. <> wrote:
> Hi Folks,
>
> In this book [1] the author says that the members of the HTML5 working group have identified recurring JavaScript patterns and then created corresponding markup:
>
>   When JavaScript was introduced into web browsers, it
>   was immediately seized upon for two tasks: Image rollovers
>   and Form enhancements. When CSS came along with its
>   :hover pseudo-class, web designers no longer needed to reach
>   for JavaScript just to achieve a simple rollover effect.
>
>   This is a recurring trend. If a pattern is popular enough, it
>   will almost certainly evolve from requiring a scripted solution
>   to something more declarative.
>
>   ...
>
>   Following the same migratory pattern from scripted to declarative
>   solutions, the [HTML5] specification introduces many new form
>   enhancements.
>
>   ...
>
>   HTML5--it's paving a cowpath ...
>
>
> Another way of saying this is: HTML5 has migrated imperative code to declarative markup.
>
> This is exciting.
>
>
> The book gives this example of migrating imperative code to declarative markup:
>
>    Here's a common DOM Scripting pattern, often used for
>    search forms:
>
>    1. When a form field has no value, insert some placeholder text into it.
>
>    2. When the user focuses on that field, remove the placeholder text.
>
>    3. If the user leaves the field and the field still has no value, reinstate the
>       placeholder text.
>
>    In an HTML5 document, you can simply use the placeholder attribute:
>
>    <input id="hobbies" name="hobbies" type="text" placeholder="Owl stretching">
>
>
> The HTML language is evolving by diligently observing usage patterns and then creating equivalent markup. Thus, there is a slow but steady progression away from the need for imperative code to declarative solutions.
>
> Cool.
>
> How has XML evolved? Can you cite examples of where usage patterns have been observed and then equivalent declarative solutions have been provided?
>
> /Roger
>
> [1] "HTML5 For Web Designers" by Jeremy Keith, p. 40-43.
>
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