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

"Murray S. Kucherawy" <superuser@gmail.com> Mon, 08 April 2013 06:55 UTC

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Date: Sun, 7 Apr 2013 23:55:26 -0700
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From: "Murray S. Kucherawy" <superuser@gmail.com>
To: Erik Wilde <dret@berkeley.edu>
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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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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.

-MSK


On Sun, Apr 7, 2013 at 10:41 PM, Erik Wilde <dret@berkeley.edu> wrote:

> hello francis.
>
>
> On 2013-04-07 13:38 , Francis Galiegue wrote:
>
>> On Fri, Apr 5, 2013 at 8:39 PM, Francis Galiegue <fgaliegue@gmail.com>
>> wrote:
>>
>>> Let us say that there is a variable called "list", whose value is an
>>> empty list:
>>> list = []
>>> Now let us have this template:
>>> X{.list}
>>> Should the expansion be "X" or "X."? And, more importantly, why?
>>>
>> Any insights? I have read the spec by and large (RFC 6570) and still
>> cannot figure it out...
>>
>
> https://github.com/dret/**uritemplate-test/blob/master/**
> spec-examples-by-section.json<https://github.com/dret/uritemplate-test/blob/master/spec-examples-by-section.json>(line 234) says it's "X", but i am really interested in the "why"
> explanation as well. http://tools.ietf.org/html/**rfc6570#section-3.2.5<http://tools.ietf.org/html/rfc6570#section-3.2.5>says that "for each defined variable in the variable-list, append '.' to
> the result string and then perform variable expansion", and i cannot find
> any text saying that an empty list is considered to be undefined. i have
> read the spec recently and never looked at this particular case, but
> without looking at the test cases i would have said it has to be expanded
> to "X." and not "X".
>
> cheers,
>
> dret.
>
> --
> erik wilde | mailto:dret@berkeley.edu  -  tel:+1-510-2061079 |
>            | UC Berkeley  -  School of Information (ISchool) |
>            | http://dret.net/netdret http://twitter.com/dret |
>
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