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Re: Production 21 (and others)



On Thu, 30 Jan 1997 22:32:49 -0500 Dave Peterson said:
>At 4:30 PM 1/30/97, lee@sq.com wrote:
>
>>Folks, please stop this.
>>It won't help implementors.
>>It won't help users.
>> ...
>Quite.  There is no rule engraved in stone that every aspect and
>restriction of the language must be captured in the productions.  That
>which can without terrible complication should (8879 probably erred the
>other way) but there is no point in evolving more and more complicated
>productions except as an academic exercise.  I too vote to kill this
>track.

OK, I'll drop it.  Before I do, I will just register my continued
opinion that the syntax of XML should be wholly explicit, where
mechanisms as simple as regular expressions suffice to describe it.

Indirection and hand-waving of the type recommended by Lee and Dave
are a recipe for inconsistent and incompatible implementations.  If
this recent indulgence in academic exercises in regular-expression
writing has shown anything, it is that a surprising number of
intelligent people with an interest in parsing and grammars can *fail*
to formalize them correctly when working from a natural-language
description, and trying to express them without recourse to scanning
modes.

I think having full regular expressions defining comments, etc., is in
fact useful to implementors.  If not, then, well, it's an academic
exercise.  Since my salary, and the time I spend on XML, are paid by
an academic institution, I make no apology for being interested in
academic exercises.

C. M. Sperberg-McQueen