dingbat@c... (Andy Dingley) wrote in message news:<28200a19.0405240308.2a1b5328@p...>...
> lkrubner@g... (lawrence) wrote in message news:<da7e68e8.0405221211.29ab7b56@p...>...
> 
> > I'm stumped when I think of all the possible user inputs that can mess
> > up an RSS feed. 
> 
> Can't be done.  Never was possible - users are just too inventive.
> 
> Instead, look at it the other way. Find the set of all things that are
> _valid_ RSS and exclude anything else.  This is a smaller set than the
> invalid stuff, and it's better documented. If you _only_ allow the
> valid sequences, then you have implicitly forbidden all the invalid
> stuff.
> 
> Definitely read this
> http://diveintomark.org/archives/2004/02/04/incompatible-rss

Thanks for the link to the Mark Pilgrim article. Despite the obvious
anti-Dave Winer bias in the article, I thought it was very good and
very informative.

I like your suggested style for moving forward but don't understand
how to do it. Should I take an input (when a user posts) and take
every character and put it into an array and then test it against an
array full of those character's that are allowed? That seems
cumbersome, though it only happens when the user inputs stuff, so
being cumbersome at that point isn't lethal. But is there a more
graceful way to validate the input?