Re: [yang-doctors] Identities vs enums

Martin Bjorklund <mbj@tail-f.com> Thu, 29 August 2019 12:13 UTC

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Date: Thu, 29 Aug 2019 14:13:33 +0200 (CEST)
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Subject: Re: [yang-doctors] Identities vs enums
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Ladislav Lhotka <lhotka@nic.cz>; wrote:
> On Thu, 2019-08-29 at 10:24 +0000, Rob Wilton (rwilton) wrote:
> > I doubt that this is the first time that this has come up …
> >  
> > draft-ietf-netmod-intf-ext-yang-07, defines 3 identities (along with a base
> > identity) for loopback configuration: “loopback-internal”, “loopback-line” and
> > “loopback-connector”.
> >  
> > One of the reviewers is complaining that the “loopback-“ prefix in the
> > identity is redundant and noisy.  I.e. he doesn’t like having to write
> > loopback=’loopback-internal’, and would like to be able to write
> > loopback=’internal’ instead.
> >  
> > His main suggestion is to move these loopback (or perhaps just the identities)
> > to a separate YANG module so that they don’t need to define a “loopback-“
> > prefix.
> >  
> > There seem to be some choices here:
> > (1) Keep with identities with a "loopback-" prefix.  This causes
> > loopback='loopback-internal'
> > (2) Keep with identities, but loose the common prefix, i.e. the identities
> > become "internal", "line", "connector".  Given the size of the module, the
> > likelihood of an identity naming clash in future seems quite small, but they
> > are somewhat generic terms.
> > (3) Use shorter identity names, but also put them in a separate types module
> > (as requested by the reviewer).
> > (4) Use an enum rather than identities.  Although this has the potential issue
> > that the enum cannot be extended (which I’m wondering if this is something
> > that we should consider changing in the hypothetical YANG Next).
> 
> I would go for (2).

+1  (provided you really need the flexibility!)

> In fact, the namespace for identity names probably needn't be module-wide, I
> think it would be perfectly fine to require unique names only for identities
> derived from the same base.

Yes that would have worked as well.  But it would have a big impact on
implementations that use the fact that they are unique...


/martin



> 
> Lada
> 
> >  
> > Personally, I’m toying with changing to 4 or perhaps 2.  I’m not keen on 3.
> >  
> > Any thoughts or opinions from the YANG doctors?
> >  
> > Thanks,
> > Rob
> >  
> > _______________________________________________
> > yang-doctors mailing list
> > yang-doctors@ietf.org
> > https://www.ietf.org/mailman/listinfo/yang-doctors
> -- 
> Ladislav Lhotka
> Head, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
> 
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