Re: adding {}s to grammar to address I18N-ISSUE-189

On 10/07/2012 03:10 PM, Eric Prud'hommeaux wrote:
>
> On Oct 7, 2012 10:35 AM, "Gavin Carothers" <gavin@carothers.name 
> <mailto:gavin@carothers.name>> wrote:
> >
> > On Sun, Oct 7, 2012 at 5:32 AM, Eric Prud'hommeaux <eric@w3.org 
> <mailto:eric@w3.org>> wrote:
> > > The LC grammar includes a LANGTAG production
> > >
> > >   [144s] LANGTAG ::= '@' [a-zA-Z]+ ('-' [a-zA-Z0-9]+)*
> > >
> > > which doesn't match the one in BCP 47
> > >
> > >          obs-language-tag = primary-subtag *( "-" subtag )
> > >          primary-subtag   = 1*8ALPHA
> > >          subtag           = 1*8(ALPHA / DIGIT)
> > >
> > > (Basically, Turtle is too liberal in what it permits in a LANGTAG.)
> > > The proposal from I18N was to reference
> > > http://tools.ietf.org/html/bcp47#section-2.1
> > > which could mean one of:
> > >
> > > 1 remove the production rule and include instead (coursly) href 
> the bcp47 defn.
> > > 2 preserve our production and href the bcp47 rule informatively
> > > 3 preserve our production and href the bcp47 rule normatively
> > > 4 align our production and href the bcp47 rule normatively
> > >
> > > I've mocked up #4 in the editor's draft (my pref). See the last
> > > sentence of
> > > 
> http://www.w3.org/2011/rdf-wg/wiki/I18n-Comments#189:_.5BS.5D_reference_obs-language-tag_instead_of_defining_your_own
> > > for all the links.
> >
> > None of 1-4 provides an enhancement to the state of language tag
> > parsing in Turtle. In order to use the grammar to test for a valid
> > language tag it must be compared to the complete registration list,
> > and be a legal composition. For even the lower bar of testing for a
> > well formed language tag a much more complex grammar must be used. All
> > of these solutions would simply add complexity without any real gain
> > to anyone. RDF Concepts already requires, with a MUST no less,
> > that "The language tag must be well-formed according to section
> > 2.2.9", these additions to Turtle aren't enough to do that. Either we
> > need to go all the way and specify the exhaustive grammar for well
> > formedness or leave this alone and let something up stream of the
> > parser confirm well formedness.
>
> Tightening up the grammer for language tags provides exactly the 
> enhancement that the I18N group recommends. I am sympathetic to their 
> proposal, noting that it parallels our treatment of IRIs.
>

(oh, right....   the treatment of IRIs to which I vote -0.975[1] on.   
so, I'll just stay out of this.       -s)


[1] That means I'll keep a civil tongue about that decision, and support 
it, until after about 1/4 of a beer.  :-)

> We don't delve into scheme specific validation, but our production is 
> still intend to eliminate crap up front.
>
> > --Gavin
> >
> >
> > > --
> > > -ericP
> > >
>