Re: Seeking clarification for "undefined" as a literal value

This does have interesting implications for (at least) aria-current.
According to the ARIA spec:

    The aria-current attribute is an enumerated type. Any value not
    included in the list of allowed values should be treated by
    assistive technologies as if the value true had been provided. If
    the attribute is not present or its value is an empty string, the
    default value of false applies and the aria-current state must not
    be exposed by user agents or assistive technologies.

Thus the language is consistent with what Rich said, which means: If the
value of aria-current is undefined (in the sense of a value having not
been provided), the default of false applies, the element is not
current, and the aria-current state must not be exposed. BUT, if the
value of aria-current is "undefined" (a string literal), then we have a
value not included in the list of allowed values, which should be
treated as if aria-current were set to true (which means the
aria-current state must be exposed by user agents).

The fact that the results of undefined and "undefined" are expected to
be the complete opposite gives me a headache.

Also, looking at the Core AAM, aria-current is undefined is "not
mapped":
https://rawgit.com/w3c/aria/master/core-aam/core-aam.html#ariaCurrentUndefined.
I guess Joseph thinks undefined means not defined? (To be honest, that's
how my brain works too.) And I guess we need to add both flavors of
undefined to Core AAM?

--joanie

On 06/29/2017 01:47 PM, Rich Schwerdtfeger wrote:
> Aaron, 
> 
> The spec. clearly states that (see aria-checked) that “undefined” is the
> (default). If nothing is specified that is what is assumed the value is.
> If the author has not set aria-checked on the role that supports the
> aria-checked states then the default is undefined. When it says default
> it is very clear. Had default not been indicated then I agree there
> would be confusion. 
> 
> So, “undefined” is a valid value. … so is leaving the attribute off
> altogether. 
> 
> In aria 1.0 here is a test example for aria-grabbed being set to
> “undefined” from the Candidate Recommendation test harness: 
> 
> https://dvcs.w3.org/hg/pfwg/raw-file/default/ARIA/1.0/tests/test-files/roles-properties-global/roles-properties-global-main-aria-grabbed-undefined.html
> 
> This passed candidate recommendation and therefor we had working
> implementations.
> 
> The important thing to remember is the default value. So, programmers
> can leave it off altogether. 
> 
> Rich 
> 
> 
> Rich Schwerdtfeger
> 
> 
> 
> 
>> On Jun 29, 2017, at 1:32 PM, Aaron Leventhal <aleventhal@google.com
>> <mailto:aleventhal@google.com>> wrote:
>>
>> As I understand ARIA, a possible value of "undefined" means the
>> attribute is not present. If undefined is also the default, then a
>> value of "" is equivalent. However, I would not expect a user agent to
>> process the literal string "undefined" as undefined.
>>
>> Was there an expectation somewhere that the literal string "undefined"
>> should be treated as attribute not present? 
>>
>> I feel that the ARIA 1.1 spec could be more clear here:
>>
>> 'The "undefined" value, when allowed on a state or property, is an
>> explicit indication that the state or property is not set. The value
>> is used on states and properties that support tokens, and the
>> "undefined" value is a string that is one of the allowed tokens. It is
>> also used on some states and properties that accept true/false values,
>> when "undefined" has a different meaning than "false".'
>>
>> Perhaps when undefined is discussed it should not be put in quotes --
>> to programmers this means literal string. Mostly, CORE-AAM does this,
>> but it does have one place under disallowed values that discusses
>> "undefined" as a literal string. It does not, however, discuss the
>> "undefined" literal as an allowed value.
>>
>> Can someone provide more clarity for our implementation? I'd like to
>> see more clarity in both specs.
>>
>> Thank you,
>>
>> - Aaron
>>
>>
>>
>

Received on Friday, 30 June 2017 13:10:28 UTC