Re: [netmod] json empty leaf encoding strangeness [Re: WG Last Call for draft-ietf-netmod-yang-json-04 (until 2015-06-29)]

[Ladislav Lhotka <[e-mail]>]

Carsten Bormann <[e-mail]> writes:

> On 18. Dec 2021, at 19:04, Ladislav Lhotka <[e-mail]> wrote:
>> 
>>    'foo: null'?  Doesn't that make testing for empty values a major
>>    pain?  'if (foo)' would not work.
>
> Same with »false«, which 7951 is not escaping into an array.  This
> argument simply doesn’t hold water.  As was mentioned, you would
> check »”foo” in o«, which works for null, false, and all other
> values that may happen to be falsy(*) in the platform.

The whole story is that Phil wanted to have both empty and boolean values as JSON strings. The result was a compromise, and I thought that [null] was a much better choice because, unlike "null" string, it cannot otherwise appear as a valid value of a YANG leaf.

>
>>    JSON evolved from Javascript, so it must keep the javascript
>>    meanings for these keywords.
>
> That is a common misconception that must be stamped out, but we have
> [e-mail] for that discussion.

It's not that I am defending these views. I did argue with RFC 4627, but not too hard, as this seemed like a marginal issue at that time - much more fundamental objections against the JSON representation were raised back then.

>
>> It is indeed true that tests in JavaScript cannot really distinguish between a non-existent member and member with the value of 'null'. I remember I wasn't happy about this change but I thought it wasn't a big deal.
>
> As mentioned, they can.
> And, yes, this little unnecessary complexity is not a big deal even if it is based on mistaken beliefs; every non-trivial protocol has some unburied zombies in the basement.

Right, in hindsight it was a mistake. It is also worth noting that [null] is only an on-the-wire value, so e.g. None can be used internally in Python. I have written a lot of related running code and don't find it a serious problem.  

Lada

>
> Grüße, Carsten
>
> (*) falsy: converted to false when implicitly coerced to a Boolean (Ant.: truthy)
>

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67