Juergen Schoenwaelder <[email protected]> wrote:
> On Sun, Jun 28, 2015 at 05:11:28PM +0200, Martin Bjorklund wrote:
> > Andy Bierman <[email protected]> wrote:
> > > On Sun, Jun 28, 2015 at 7:16 AM, Juergen Schoenwaelder <
> > > [email protected]> wrote:
> > >
> > > > On Wed, Jun 24, 2015 at 12:16:55PM +0200, Martin Bjorklund wrote:
> > > > > Hi,
> > > > >
> > > > > Currently we have an inconsistency in
> > > > > draft-ietf-netmod-rfc6020bis-05. With Y35, we allow type empty in
> > > > > unions. But section 7.8.2 says:
> > > > >
> > > > > A leaf that is part of the key can be of any built-in or derived
> > > > > type, except it MUST NOT be the built-in type "empty".
> > > > >
> > > > > This means that this is legal:
> > > > >
> > > > > typedef my-empty {
> > > > > type union {
> > > > > type empty;
> > > > > }
> > > > > }
> > > > >
> > > > > list foo {
> > > > > key id;
> > > > > leaf id {
> > > > > type my-empty;
> > > > > }
> > > > > ...
> > > > > }
> > > > >
> > > > > I suggest we allow type empty also in keys:
> > > > >
> > > > > NEW:
> > > > >
> > > > > A leaf that is part of the key can be of any built-in or derived
> > > > > type.
> > > >
> > > > And my understanding is that the list foo defined above will never
> > > > have an instance, correct? I assume decent compilers will continue to
> > > > create warnings when they can decide that a list will never have any
> > > > instances. (And yes, there are other ways to construct such lists, so
> > > > I am OK with removing a constraint preventing a specific case of such
> > > > useless lists.)
> > > >
> > > >
> > > I think the list can have 1 instance.
> >
> > Yes.
> >
>
> OK. I guess RFC 6020 section 9.11.2. confused me. Is the lexical
> representation not simply an empty string?
No, since the empty string in JSON is "".
A leaf of type empty doesn't have a value, thus there is no lexical
represention.
> I mean, it seems that
>
> <foo>
> <id></id>
> </foo>
>
> would be as valid as
>
> <foo><id/></foo>
Correct.
> or am I confused? And in JSON it would be this?
>
> "foo": [
> {
> "id": [null]
> }
> ]
I think this is correct.
/martin
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