> On 08 Jun 2016, at 17:22, Dale R. Worley <wor...@ariadne.com> wrote: > > Martin Bjorklund <m...@tail-f.com> writes: >> The text for "path" already says: >> >> It takes as an argument a >> string that MUST refer to a leaf or leaf-list node. > > Given what the text must mean, that's sufficient for me.
Then it's fine with me, too. Lada > > Ladislav Lhotka <lho...@nic.cz> writes: >> Which of the two "foo" leaf nodes does the path argument point at? If >> the path is interpreted in the schema tree, it may appear it is the >> one inside the choice. Yes, we all know it points at the other one, >> but will all readers of the spec come to the same conclusion? > > Well, in 9.9.2 it says: > > The "path" XPath expression is conceptually evaluated in the > following context, in addition to the definition in Section 6.4.1: > > o If the "path" statement is defined within a typedef, the context > node is the leaf or leaf-list node in the data tree that > references the typedef. > > o Otherwise, the context node is the node in the data tree for which > the "path" statement is defined. > > What's really going on is that the XPath expression will always be > evaluated in the context of a particular element of a particular data > tree, but that it can be shown to be always valid by doing a "generic > evaluation" of the expression looking at the schema tree -- the schema > tree is a generic description of all possible data trees. Of course > there are various complications because not all nodes in the schema tree > are represented in the XML tree. > > In mathematics, abstracting an operation in a particular structure to a > similar operation in a "generic" structure is called "lifting", and > using that term, it's easy to notify the reader what you're doing > without spelling out the details. What's difficult here is that it's > "obvious" what the text has to mean, but we have no simple vocabulary > for pointing that out, and the reader who is not careful might not > realize everything that is going on. > > At this point, I'm willing to ignore the issue. There doesn't seem to > be a simple way to explain the critical issue. And if the reader > attempts to work out the details of Yang processing, he eventually has > to come to the correct conclusion; there is only one self-consistent > interpretation. > > Dale > > _______________________________________________ > netmod mailing list > netmod@ietf.org > https://www.ietf.org/mailman/listinfo/netmod -- Ladislav Lhotka, CZ.NIC Labs PGP Key ID: E74E8C0C _______________________________________________ netmod mailing list netmod@ietf.org https://www.ietf.org/mailman/listinfo/netmod
