Subject: Re: [xsl] XSLT 2.0 courses? From: "Michael Kay mike@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> Date: Mon, 21 Sep 2020 11:30:40 -0000 |
When you see "respectively" used as a conjunction, you know it's English written by a native speaker of German: "his respectively her", "blue respectively green". The correct translation of "X bzw Y" in such cases is probably "X/Y", or "X or, where appropriate, Y", or "X and/or Y", or "X or Y respectively", none of which work in a programming language! Michael Kay Saxonica > On 21 Sep 2020, at 12:18, Imsieke, Gerrit, le-tex gerrit.imsieke@xxxxxxxxx <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote: > > In its original sense, bzw. (beziehungsweise) means 'respectively', but yes, it has assumed the additional meaning of something like 'or', 'or else', or 'or rather'. > > https://en.m.wiktionary.org/wiki/beziehungsweise > > 'or else' is appropriate for the operator, but it might be a nightmare grammar-wise (XPath grammar, not English grammar). > > > On 21.09.2020 13:01, Michael Kay mike@xxxxxxxxxxxx wrote: >> 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.imsieke@xxxxxxxxx <mailto:gerrit.imsieke@xxxxxxxxx> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> 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@xxxxxxxxxxxx <mailto: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> <mailto:gerrit.imsieke@xxxxxxxxx <mailto:gerrit.imsieke@xxxxxxxxx>> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> <mailto: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 $b"? I'm not sure which one will seem more natural to most users. >>>>> >>>>> Gerrit >>>>> >>>>> On 21.09.2020 10:46, Michael Kay mike@xxxxxxxxxxxx <mailto:mike@xxxxxxxxxxxx> <mailto:mike@xxxxxxxxxxxx <mailto:mike@xxxxxxxxxxxx>> wrote: >>>>>> I've been proposing ($a otherwise $b) to meet this requirement: it returns $a unless it's an empty sequence, in which case it returns $b. >>>>>> For example @price - (@discount otherwise 0) >>>>>> It's actually implemented in Saxon 10 if you switch syntax extensions on. >>>>>> Michael Kay >>>>>> Saxonica >>>>>>> On 21 Sep 2020, at 02:34, Pieter Lamers pieter.lamers@xxxxxxxxxxxx <mailto:pieter.lamers@xxxxxxxxxxxx> <mailto:pieter.lamers@xxxxxxxxxxxx <mailto:pieter.lamers@xxxxxxxxxxxx>> <mailto:pieter.lamers@xxxxxxxxxxxx <mailto:pieter.lamers@xxxxxxxxxxxx> <mailto:pieter.lamers@xxxxxxxxxxxx <mailto:pieter.lamers@xxxxxxxxxxxx>>> <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>> <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx <mailto:xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>>>> wrote: >>>>>>> >>>>>>> Hi, >>>>>>> >>>>>>> An avid user of ($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, $b)[1] will return just the first item in the sequence, 'one', and not 'one','two','three', which might be what you want to achieve in this quasi shorthanded /if/else /construction. >>>>>>> >>>>>>> Not that you wouldn't know, Liam, just as a heads up to some others in this audience who might not. >>>>>>> >>>>>>> Best, >>>>>>> Pieter >>>>>>> >>>>>>> On 19/09/2020 01:54, Liam R. E. Quin liam@xxxxxxxxxxxxxxxx <mailto:liam@xxxxxxxxxxxxxxxx> <mailto:liam@xxxxxxxxxxxxxxxx <mailto:liam@xxxxxxxxxxxxxxxx>> wrote: >>>>>>>> On Fri, 2020-09-18 at 19:31 +0000, Wendell Piezwapiez@xxxxxxxxxxxxxxx <mailto:Piezwapiez@xxxxxxxxxxxxxxx> <mailto:Piezwapiez@xxxxxxxxxxxxxxx <mailto:Piezwapiez@xxxxxxxxxxxxxxx>> >>>>>>>> wrote: >>>>>>>>> Hi, >>>>>>>>> >>>>>>>>> In addition to Liam's list I think there are a couple more vital >>>>>>>>> features >>>>>>>>> one needs to get a taste of in XSLT 2.0 or XSLT 3.0, if one has been >>>>>>>>> subsisting on an XSLT 1.0 diet: >>>>>>>>> >>>>>>>>> * <xsl:for-each-group> and its uses >>>>>>>>> * temporary trees - >>>>>>>>> * regex support in functions and xsl:analyze-string >>>>>>>>> * tunnel parameters? >>>>>>>> Yeah, those are all huge, although i think easier to learn than things >>>>>>>> like ($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 $c, so it's a shortcut for >>>>>>>> <xsl:sequence select="if ($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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