Re: [netmod] augment and if-feature

[Martin Bjorklund <[e-mail]>]

Phil Shafer <[e-mail]> wrote:
> Martin Bjorklund writes:
> >Phil Shafer <[e-mail]> wrote:
> >> Martin Bjorklund writes:
> >> >> What are your thoughts on this? Surely, an augment should not have to
> >> >> contain if-feature statements of all parents of the augmented node.
> >> >
> >> >The spec says:
> >> >
> >> >   When a server implements a module containing an "augment" statement,
> >> >   that implies that the server's implementation of the augmented module
> >> >   contains the additional nodes.
> >> >
> >> >Compare with a simple augment of a node w/o an if-feature.  In this
> >> >case, if the server implements the augmenting module, it MUST also
> >> >implement the augmented module.
> >> 
> >> It implements the module, but it doesn't implement the nodes
> >> since it doesn't express the feature.  IMHO this is a tool
> >> bug and/or an errata,since otherwise one has to carry features
> >> forward, repeating the if-feature using the original modules
> >> prefix:feature-name on every augment of feature-based nodes.
> >
> >Well, I agree that it would have been better to state that if a server
> >doesn't implement the augment target, then it doesn't implement the
> >augment either.  But the text is pretty clear; this is not how it
> >works.  This is not appropriate to "fix" in an errata.
> 
> I'm missing the part of the text that's clear.  The above quoted
> section certainly doesn't say this.  That text is saying "if you
> implement a module that augments a set of nodes, then the server's
> schema for that original set of nodes now includes the new set of
> nodes".  It's referring to schema nodes.

It explicitly says that server's *implementation* of the augmented
module contains the additional nodes.

If you don't advertise a certain module, I don't think you can claim
that your implementation contains that module.

And similarly, if you don't advertise a feature, I don't think you can
claim that your implementation implements nodes that are conditional
on that feature.

> And if those schema nodes are conditional based on if-feature, then
> those nodes are still in the schema, but are not supported by a
> server unless the if-feature condition evaluates to true.
> 
> I don't see a conflict,

> it's just a case that we didn't think about
> or write about.

This I agree with.

> It's a case that's not clearly handled in the spec,
> for which reasonable implementations can disagree.  That's a bug
> in the spec and it that can be clarified via errata.
> 
> Thanks,
>  Phil
> 


/martin