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

Joe Gregorio <joe@bitworking.org> Wed, 17 April 2013 14:03 UTC

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From: Joe Gregorio <joe@bitworking.org>
To: Erik Wilde <dret@berkeley.edu>
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Subject: Re: [apps-discuss] Question about URI template and expansion of an empty list
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Sorry for the delay in responding.

On Mon, Apr 8, 2013 at 1:41 AM, 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
> (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 says
> that

The answer is in the text you quote:

"for each defined variable in the variable-list, append '.' to the
result string and then perform variable expansion"

The set of variables in the variable list is the empty set, so no '.'
is appended.

I agree that if this is confusing an addendum is in order.

  -joe

>, 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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Joe Gregorio        http://bitworking.org