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Re: [netmod] Does the YANG "status" statement inherit from its parent node?

Martin Bjorklund <mbj@tail-f.com> Wed, 21 December 2016 11:03 UTC

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Date: Wed, 21 Dec 2016 12:03:06 +0100
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To: lhotka@nic.cz
From: Martin Bjorklund <mbj@tail-f.com>
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Subject: Re: [netmod] Does the YANG "status" statement inherit from its parent node?
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Ladislav Lhotka <lhotka@nic.cz> wrote:
> 
> > On 21 Dec 2016, at 10:32, Martin Bjorklund <mbj@tail-f.com> wrote:
> > 
> > Ladislav Lhotka <lhotka@nic.cz> wrote:
> >> Martin Bjorklund <mbj@tail-f.com> writes:
> >> 
> >>> Robert Wilton <rwilton@cisco.com> wrote:
> >>>> Hi,
> >>>> 
> >>>> The definition of "status" in RFC 7950 in section 7.21.2 (full text
> >>>> below), states:
> >>>> 
> >>>> If no status is specified, the default is "current".
> >>>> 
> >>>> From my interpretation of the text in the draft, this implies that the
> >>>> status of the "new" child leaf in the following example is "current",
> >>>> and that this example is allowed!
> >>>> 
> >>>> My questions are:
> >>>> - Is my interpretation of the current text correct?
> >>> 
> >>> Yes.
> >>> 
> >>>> - Is this actually the best behaviour, or should it inherit like the
> >>>>   config statement?
> >>> 
> >>> I think the idea was that if the status != current, it is better for
> >>> the reader if it is explicitly stated.
> >>> 
> >>>> Should I raise an errata for this?
> >>> 
> >>> No.
> >>> 
> >>> However, we could have said that a current node under a deprecated
> >>> node (etc) in the same module is an error, in order to force people
> >>> (through the useage of YANG validators) to detect and fix this.
> >> 
> >> Since "current" is the default, correctly deprecating a subtree would
> >> mean to explicitly add the "status" statement to every single node in
> >> the subtree.
> > 
> > Yes.
> > 
> >> I think that "obsolete" should apply to the whole subtree, no matter
> >> what status descendants have, and "deprecated" should apply to the whole
> >> subtree except for parts that are obsolete.
> > 
> > Maybe, but this is not how it works in YANG 1 and 1.1.  For the
> > reasoning behind this, see above.  Maybe this is not perfect, and
> > something that we should look into if we update YANG.  But I don't
> > think this is a problem.
> 
> I think it is a problem. We can see a lot of these things before
> long because of the update rules. For example, it may apply to all
> the *-state trees, and tagging every single node therein with
> "deprecated" or "obsolete" is a useless exercise.

I don't think it is a useless exercise.  It helps the reader to
quickly see that a node is deprecated, without having to search the
text for all ancestors' status.


/martin

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