Re: [xsl] XSLT 2.0 courses?

["David Carlisle d.p.carlisle@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

On Mon, 21 Sep 2020 at 15:08, Wendell Piez wapiez@xxxxxxxxxxxxxxx <
xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

> Hi,
>
> Aside from the name question (I'd maybe like first-available()?) the
> question arises, what would be the difference between
> first-defined(($a,$b,$c)) and head(($a,$b,$c)) or ($a,$b,$c) => head() as
> the case may be?
>

It would need to be an overloaded function like concat taking any number of
arguments so first-defined($a,$b,$c)  if you ,-join the lists first you no
longer can return $a if non empty,  head(($a,$b,$c)) is the head of the
sequence ($a,$b,$c) which is the flattened sequence of items from $a $b and
$c so would just return the first item in $a not all of $a.

David




> Cheers, Wendell
>
>
> On Mon, Sep 21, 2020 at 9:41 AM Graydon graydon@xxxxxxxxx <
> xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:
>
>> On Mon, Sep 21, 2020 at 01:25:56PM -0000, Chris Papademetrious
>> christopher.papademetrious@xxxxxxxxxxxx scripsit:
>> > Good point. Perhaps this could be handled by chaining them?
>> >
>> > $a otherwise $b otherwise $c otherwise $default
>>
>> I think "otherwise" is fine for the pair case!
>>
>> It's clearer and easier to read than ($a,$b)[1] and it'll be easier to
>> search for in documentation.
>>
>> Chaining otherwise as you propose doesn't strike me as clearer or easier
>> to read; the location of the implicit parentheses is extremely important
>> in that example and as soon as the values are the least bit complex all
>> the parens will likely need to be made explicit.
>>
>> On the other hand, we've already got a concept of sequence, and commas,
>> so ($a,$b,$c,$default) => first-defined()
>>
>> strikes me as clearer and easier to read than chaining "otherwise".
>> Could even add a two-parameter version so the second parameter defines
>> how to handle values which are false(). :)
>>
>> --
>> Graydon Saunders  | graydonish@xxxxxxxxx
>> CC&s oferC)ode, C0isses swC! mC&g.
>> -- Deor  ("That passed, so may this.")
>>
>>
>
> --
> ...Wendell Piez... ...wendell -at- nist -dot- gov...
> ...wendellpiez.com... ...pellucidliterature.org... ...pausepress.org...
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