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Re: XSLT 2.0 courses?
Thank you, this is convincing.
One might consider naming the 'otherwise' operator 'alternatively', but
this is not the hill I'm going to die on.
Gerrit
On 21.09.2020 12:53, Michael Kay mike@xxxxxxxxxxxx wrote:
Well, I thought about using EBV, so it means (if ($a) then $a else $b),
but zero is falsey, so you get surprises with, for example
@price * (1 + (@VAT_Rate otherwise 0.2))
which potentially gives the wrong answer if @VAT_Rate is present but
zero. And it also gets complicated with atomization: if the attribute is
present but set to a zero length string, which way do you go?
Michael Kay
Saxonica
On 21 Sep 2020, at 11:21, Imsieke, Gerrit, le-tex
gerrit.imsieke@xxxxxxxxx <mailto:gerrit.imsieke@xxxxxxxxx>
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> wrote:
If the boolean variable $a is false() instead of an empty sequence,
$a otherwise $b
will return false(). This is the specified behaviour, but I find it a
bit counterintuitive. I have a slight preference for the otherwise
operator to return $b if $a is false().
Have you thought about defining the otherwise operator as "it returns
$a unless it's an empty sequence or a boolean value equal to false(),
in which case it returns $b"? I'm not sure which one will seem more
natural to most users.
Gerrit
On 21.09.2020 10:46, Michael Kay mike@xxxxxxxxxxxx
<mailto:mike@xxxxxxxxxxxx> wrote:
I've been proposing ($a otherwise $b) to meet this requirement: it
returns $a unless it's an empty sequence, in which case it returns $b.
For example @price - (@discount otherwise 0)
It's actually implemented in Saxon 10 if you switch syntax extensions on.
Michael Kay
Saxonica
On 21 Sep 2020, at 02:34, Pieter Lamers pieter.lamers@xxxxxxxxxxxx
<mailto:pieter.lamers@xxxxxxxxxxxx>
<mailto:pieter.lamers@xxxxxxxxxxxx
<mailto:pieter.lamers@xxxxxxxxxxxx>>
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx
<mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>>> wrote:
Hi,
An avid user of ($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, $b)[1] will return just the first item in the sequence,
'one', and not 'one','two','three', which might be what you want to
achieve in this quasi shorthanded /if/else /construction.
Not that you wouldn't know, Liam, just as a heads up to some others
in this audience who might not.
Best,
Pieter
On 19/09/2020 01:54, Liam R. E. Quin liam@xxxxxxxxxxxxxxxx
<mailto:liam@xxxxxxxxxxxxxxxx> wrote:
On Fri, 2020-09-18 at 19:31 +0000, Wendell
Piezwapiez@xxxxxxxxxxxxxxx <mailto:Piezwapiez@xxxxxxxxxxxxxxx>
wrote:
Hi,
In addition to Liam's list I think there are a couple more vital
features
one needs to get a taste of in XSLT 2.0 or XSLT 3.0, if one has been
subsisting on an XSLT 1.0 diet:
* <xsl:for-each-group> and its uses
* temporary trees -
* regex support in functions and xsl:analyze-string
* tunnel parameters?
Yeah, those are all huge, although i think easier to learn than things
like ($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 $c, so it's a shortcut for
B B B B <xsl:sequence select="if ($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
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