Re: [xml-dev] Parsing XML with anything but

["Simon St.Laurent" <simonstl@simonstl.com>]

On 12/9/13 9:39 PM, Amelia A Lewis wrote:
> I should probably avoid this argument. *sigh*
Yes, you should.  The shape of the world does actually differ for many 
cases.

> On Mon, 09 Dec 2013 17:08:14 -0500, Simon St.Laurent wrote:
> > Yes, it's true that writing applications that apply regular
> > expressions or other text processing to "complete" XML can be
> > dangerous.  That doesn't mean that people doing that are stupid or
> > poorly trained, however, and neither does it mean that they haven't
> > tried their local XML toolsets first and found them wanting.
> Simon, I'm afraid that I have to differ with you. Anyone who uses
> regular expressions for a grammar that relies extensively on parity is
> either stupid or poorly trained. Sure, you can do text processing (==
> processing of element names, attribute names, attribute values, and
> text node contents (without distinguishing reliably between them))
> using regular expressions. You can't reliably establish XML structure,
> because the syntax of XML is specified by a grammar that cannot be
> handled by a finite automaton, that is not a regular grammar.
No, you can't do any of those things.  However, there is an enormous 
class of tasks for which those issues simply do not matter.

They arise for two reasons:

1) People are performing tasks that are simple enough that even those 
drawbacks will not get them in trouble.

2) People are applying these tools to subsets of XML for which these 
issues are unlikely to apply.

Yes, in general, XML is capable of infinite headache-inducement for 
those foolish enough to approach it with regexes or pretty much any 
tools that were not written as XML parsers.  My time spent writing a 
markup parser taught me many of them.

However, the subset of cases is common enough that condescension is foolish.

> Using regular expressions to handle XML (except in specialized
> circumstances, possibly including "s/Soviet Union/Russian
> Federation/g", but almost certainly not including "s/soviet/russian/gi"
> because the latter (apart from demonstrating a lamentable historical
> illiteracy (speaking as a formally-trained historian of the Soviet
> Union, once upon a time)) is too apt to change attribute or element
> names) is, to follow the pattern of analogy common in recent threads,
> about the equivalent of handing a carpenter framing lumber and screws
> and watching him whip out his ... hammer. A carpenter who does so
> (except in specialized circumstances) is aptly regarded as stupid or
> poorly trained (generically: not competent to handle the problem). More
> to the point, the structure such a carpenter creates is going to
> *fail*, which means it is appropriate for other carpenters to say "that
> ain't right."
Yes.  But vast quantities of processing work in contexts where there are 
no screws involved, just nails.  That is even true for... gasp... 
markup.  (And yeah, natural language processing is hard.  That's not a 
surprise.)

I get that people on an XML list freak out when people don't follow all 
the rules we think we've established.  We need to find a better way to 
handle our freaking out than sputtering about "either stupid or poorly 
trained" people who "don’t have the inclination, patience or capability 
to fully understand your language of choice."

It makes us look bad, not them.  It hurts our cause(s), and doesn't help 
theirs.

That attitude is exactly why I've largely given up speaking about XML to 
broader audiences and retreated to "markup".  It doesn't carry the 
elitist baggage or visions of infinite complexity.

Thanks,
--
Simon St.Laurent
http://simonstl.com/