Re: [apps-discuss] Question about URI template and expansion of an empty list

James M Snell <jasnell@gmail.com> Mon, 08 April 2013 14:51 UTC

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From: James M Snell <jasnell@gmail.com>
Date: Mon, 8 Apr 2013 07:50:45 -0700
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To: "Murray S. Kucherawy" <superuser@gmail.com>, Joe Gregorio <joe@bitworking.org>
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Cc: IETF Apps Discuss <apps-discuss@ietf.org>
Subject: Re: [apps-discuss] Question about URI template and expansion of an empty list
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"empty_keys" is not defined explicitly as an empty associative array.
The only definition given for "empty_keys" in section 3.2 is
"empty_keys := []" which is semantically and structurally identical to
an empty list. So to amend your rules, we have:

- an undefined value produces "X"
- a defined-but-empty string produces "X."
- a defined-but-empty list/associative-array produces "X"

- James


On Mon, Apr 8, 2013 at 6:53 AM, Murray S. Kucherawy <superuser@gmail.com> wrote:
> empty_keys (defined in 3.2) is an empty associative array, not an empty
> list.  So we have:
>
> - an undefined value produces "X"
> - a defined-but-empty string produces "X."
> - a defined-but-empty associative array produces "X"
>
> It's not clear to me that there's a pattern here yielding an obvious answer
> for which of the two a defined-but-empty list should produce.
>
>
> On Mon, Apr 8, 2013 at 6:37 AM, James M Snell <jasnell@gmail.com> wrote:
>>
>> Am I missing something subtle about the question? The examples in Section
>> 3.2.5 show "X{.empty_keys}" where empty keys = [], expands to "X". Given
>> that the list is empty, there's nothing to expand it into.
>>
>> On Apr 8, 2013 5:54 AM, "Francis Galiegue" <fgaliegue@gmail.com> wrote:
>>>
>>> On Mon, Apr 8, 2013 at 8:55 AM, Murray S. Kucherawy <superuser@gmail.com>
>>> wrote:
>>> > I'm inclined to think it's "X." for the same reason "X{.empty}" is
>>> > "X.",
>>> > which is to say that an empty list, like an empty string, isn't
>>> > undefined,
>>> > but there is indeed nothing to expand.
>>> >
>>> > Either way, there may be grounds for an erratum here.  The RFC does
>>> > talk
>>> > about handling empty strings, but not empty lists.  The closest is
>>> > Section
>>> > 3.2.1 which talks about "expansion of a defined, non-empty value",
>>> > meaning
>>> > defined, empty values aren't explicitly covered in the prose as far as
>>> > I can
>>> > see.
>>> >
>>>
>>> Similarly, it doesn't talk about extending empty maps.
>>>
>>> --
>>> Francis Galiegue, fgaliegue@gmail.com
>>> JSON Schema in Java: http://json-schema-validator.herokuapp.com
>>> _______________________________________________
>>> apps-discuss mailing list
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>>> https://www.ietf.org/mailman/listinfo/apps-discuss
>
>