On Wed, Jun 08, 2016 at 01:16:28PM +0200, Martin Bjorklund wrote:
> Juergen Schoenwaelder <[email protected]> wrote:
> > On Wed, Jun 08, 2016 at 12:29:59PM +0200, Martin Bjorklund wrote:
> >
> > > > > Note that this is legal YANG:
> > > > >
> > > > > leaf type {
> > > > > type string;
> > > > > }
> > > >
> > > > So keywords aren't reserved; they can also be used as identifiers.
> > >
> > > Yes.
> >
> > > > That's a lot clearer. Though you can shorten it to:
> > > >
> > > > An unquoted string is any sequence of characters that is not a
> > > > keyword, and does not contain any space, tab, or newline
> > > > characters, a single or double quote character, a semicolon (";"),
> > > > braces ("{" or "}"), or comment sequences ("//", "/*", or "*/").
> > >
> > > Thanks, better.
> >
> > The does the 'is not a keyword' not contratict the example shown
> > above? My reading of the new suggested text would make me believe
> > I would have to write the example as follows
> >
> > leaf "type" {
> > type string;
> > }
> >
> > which is different from the YANG 1.0 syntax rules I think.
>
> Note that I also wrote:
>
> > > In section 6.3 we must also do:
> > >
> > > OLD:
> > >
> > > The argument is a string, as defined in Section 6.1.2.
> > >
> > > NEW:
> > >
> > > The argument is a string or a keyword, as defined in Section 6.1.2.
>
> The alternative is to keep the current text. But it means that the
> scanner is context-dependent (logically at least).
>
> IMO it doesn't really matter - this is just a conceptual explanation;
> an implementation is free to implement this in whatever clever way it
> wants.
OK. So in combination with the other text we achieve the same result.
But personally, I think it is much clearer for an implementor if the
definition of an unquoted string does not exclude keywords, the risk
of getting inconsistencies later on scares me a bit. I rather would
like to see something like this:
An unquoted string is any sequence of characters and does not
contain any space, tab, or newline characters, a single or double
quote character, a semicolon (";"), braces ("{" or "}"), or
comment sequences ("//", "/*", or "*/").
Note that any keyword can legally appear as an unquoted string.
YANG is indeed a bit special here and I believe it helps implementors
to point this out right here where an unquoted string is defined. And
'the argument' is really a string and not a string or a keyword, which
may lead to confusion or worse wrong interpretations (despite the fact
that one might implement things this way).
/js
--
Juergen Schoenwaelder Jacobs University Bremen gGmbH
Phone: +49 421 200 3587 Campus Ring 1 | 28759 Bremen | Germany
Fax: +49 421 200 3103 <http://www.jacobs-university.de/>
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