Re: [xsl] XSLT 2.0 courses?

Perhaps we should call it "bzw" - a German word that is sadly missing from 
English.

Mike

> On 21 Sep 2020, at 11:58, Imsieke, Gerrit, le-tex 
> gerrit(_dot_)imsieke(_at_)le-tex(_dot_)de 
> <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> wrote:
>
> 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(_at_)saxonica(_dot_)com 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(_dot_)imsieke(_at_)le-tex(_dot_)de 
> > > <mailto:gerrit(_dot_)imsieke(_at_)le-tex(_dot_)de> 
> > > <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com 
> > > <mailto:xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>> 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 $b"? I'm not sure which one will seem more natural to most 
> > > users.
> > >
> > > Gerrit
> > >
> > > On 21.09.2020 10:46, Michael Kay mike(_at_)saxonica(_dot_)com 
> > > <mailto:mike(_at_)saxonica(_dot_)com> wrote:
> > > > I've been proposing ($a otherwise $b) to meet this requirement: it returns 
> > > > $a unless it's an empty sequence, in which case it returns $b.
> > > > For example @price - (@discount otherwise 0)
> > > > It's actually implemented in Saxon 10 if you switch syntax extensions on.
> > > > Michael Kay
> > > > Saxonica
> > > > > On 21 Sep 2020, at 02:34, Pieter Lamers 
> > > > > pieter(_dot_)lamers(_at_)benjamins(_dot_)nl 
> > > > > <mailto:pieter(_dot_)lamers(_at_)benjamins(_dot_)nl> 
> > > > > <mailto:pieter(_dot_)lamers(_at_)benjamins(_dot_)nl 
> > > > > <mailto:pieter(_dot_)lamers(_at_)benjamins(_dot_)nl>> 
> > > > > <xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com 
> > > > > <mailto:xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com> 
> > > > > <mailto:xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com 
> > > > > <mailto:xsl-list-service(_at_)lists(_dot_)mulberrytech(_dot_)com>>> wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > An avid user of ($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, $b)[1] will return just the first item in the sequence, 
> > > > > 'one', and not 'one','two','three', which might be what you want to 
> > > > > achieve in this quasi shorthanded /if/else /construction.
> > > > >
> > > > > Not that you wouldn't know, Liam, just as a heads up to some others in 
> > > > > this audience who might not.
> > > > >
> > > > > Best,
> > > > > Pieter
> > > > >
> > > > > On 19/09/2020 01:54, Liam R. E. Quin liam(_at_)fromoldbooks(_dot_)org 
> > > > > <mailto:liam(_at_)fromoldbooks(_dot_)org> wrote:
> > > > > > On Fri, 2020-09-18 at 19:31 +0000, Wendell 
> > > > > > Piezwapiez(_at_)wendellpiez(_dot_)com 
> > > > > > <mailto:Piezwapiez(_at_)wendellpiez(_dot_)com>
> > > > > > wrote:
> > > > > > > Hi,
> > > > > > >
> > > > > > > In addition to Liam's list I think there are a couple more vital
> > > > > > > features
> > > > > > > one needs to get a taste of in XSLT 2.0 or XSLT 3.0, if one has been
> > > > > > > subsisting on an XSLT 1.0 diet:
> > > > > > >
> > > > > > > * <xsl:for-each-group> and its uses
> > > > > > > * temporary trees -
> > > > > > > * regex support in functions and xsl:analyze-string
> > > > > > > * tunnel parameters?
> > > > > > Yeah, those are all huge, although i think easier to learn than things
> > > > > > like ($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
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