Re: [yang-doctors] Identities vs enums

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).

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.

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
>  
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Ladislav Lhotka
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