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Re: [xsl] XSLT 2.0 courses?

2020-09-21 03:46:29
I've been proposing ($a otherwise $b) to meet this requirement: it returns $a 
unless it's an empty sequence, in which case it returns $b.

For example @price - (@discount otherwise 0)

It's actually implemented in Saxon 10 if you switch syntax extensions on.

Michael Kay
Saxonica

On 21 Sep 2020, at 02:34, Pieter Lamers 
pieter(_dot_)lamers(_at_)benjamins(_dot_)nl 
<xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:

Hi,

An avid user of ($a, $b)[1] myself, which winks at TransactSQL ISNULL($a, $b) 
and MySQL IFNULL($a, $b), I do have to remind myself that $a has to be a 
single item for the if/else shortcut to work.

So, in 
let $a := ('one','two','three')
let $b := ('none')

return ($a, $b)[1] will return just the first item in the sequence, 'one', 
and not 'one','two','three', which might be what you want to achieve in this 
quasi shorthanded if/else construction.

Not that you wouldn't know, Liam, just as a heads up to some others in this 
audience who might not.
Best,
Pieter
On 19/09/2020 01:54, Liam R. E. Quin liam(_at_)fromoldbooks(_dot_)org 
<mailto:liam(_at_)fromoldbooks(_dot_)org> wrote:
On Fri, 2020-09-18 at 19:31 +0000, Wendell Piez 
wapiez(_at_)wendellpiez(_dot_)com <mailto:wapiez(_at_)wendellpiez(_dot_)com>
wrote:
Hi,

In addition to Liam's list I think there are a couple more vital
features
one needs to get a taste of in XSLT 2.0 or XSLT 3.0, if one has been
subsisting on an XSLT 1.0 diet:

* <xsl:for-each-group> and its uses
* temporary trees -
* regex support in functions and xsl:analyze-string
* tunnel parameters?
Yeah, those are all huge, although i think easier to learn than things
like ($a, 'none')[1], which are startling because XSLT 1 didn't have
sequences.

For those wondering, ($a, $b, $c, ...)[1] returns the first non-empty
non-false item out of $a, $b and $c, so it's a shortcut for
    <xsl:sequence select="if ($a) then $a else $b" />


On regular expressions - it's huge, but it's also dangerous, as e.g.
replace(price div 100, '\.\d*$', '') is not a good way to write
math:floor().

An XSLT-3-from-scratch course could easily take a full week and be
woefully incomplete. Or totally overwhelming. Or both.

On the other hand, i try & include "don't be afraid of the specs" in
the courses i teach, and then not cover every detail. So maybe it's
possible.

Liam

-- 
Pieter Lamers
John Benjamins Publishing Company
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