Subject: Re: [xsl] XSLT 2.0 courses? From: "Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> Date: Mon, 21 Sep 2020 08:46:23 -0000 |
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 $b. For example @price - (@discount otherwise 0) It's actually implemented in Saxon 10 if you switch syntax extensions on. Michael Kay Saxonica > On 21 Sep 2020, at 02:34, Pieter Lamers pieter.lamers@xxxxxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hi, > > An avid user of ($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, $b)[1] will return just the first item in the sequence, 'one', and not 'one','two','three', which might be what you want to achieve in this quasi shorthanded if/else construction. > > Not that you wouldn't know, Liam, just as a heads up to some others in this audience who might not. > Best, > Pieter > On 19/09/2020 01:54, Liam R. E. Quin liam@xxxxxxxxxxxxxxxx <mailto:liam@xxxxxxxxxxxxxxxx> wrote: >> On Fri, 2020-09-18 at 19:31 +0000, Wendell Piez wapiez@xxxxxxxxxxxxxxx <mailto:wapiez@xxxxxxxxxxxxxxx> >> wrote: >>> Hi, >>> >>> In addition to Liam's list I think there are a couple more vital >>> features >>> one needs to get a taste of in XSLT 2.0 or XSLT 3.0, if one has been >>> subsisting on an XSLT 1.0 diet: >>> >>> * <xsl:for-each-group> and its uses >>> * temporary trees - >>> * regex support in functions and xsl:analyze-string >>> * tunnel parameters? >> Yeah, those are all huge, although i think easier to learn than things >> like ($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 $c, so it's a shortcut for >> <xsl:sequence select="if ($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 > Postal Address: P.O. Box 36224, 1020 ME AMSTERDAM, The Netherlands > Visiting Address: Klaprozenweg 75G, 1033 NN AMSTERDAM, The Netherlands > Warehouse: Kelvinstraat 11-13, 1446 TK PURMEREND, The Netherlands > tel: +31 20 630 4747 > web: www.benjamins.com <http://www.benjamins.com/> > XSL-List info and archive <http://www.mulberrytech.com/xsl/xsl-list> > EasyUnsubscribe <http://lists.mulberrytech.com/unsub/xsl-list/293509> (by email <>)
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