Re: [xsl] how to create variable by comparing two variables using [not]

["Eliot Kimber ekimber@xxxxxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Looking at the XPath 3 Functions and Operators specification and searching on
"intersect" (hoping to also find "disjoint") I find this discussion:

D.4.2.3 eg:value-except
eg:value-except(	$arg1	 as xs:anyAtomicType*,
$arg2	 as xs:anyAtomicType*) as xs:anyAtomicType*
This function returns a sequence containing all the distinct items that appear
in $arg1 but not in $arg2, in an arbitrary order.

XSLT implementation

<xsl:function name="eg:value-except" as="xs:anyAtomicType*">
  <xsl:param name="arg1" as="xs:anyAtomicType*"/>
  <xsl:param name="arg2" as="xs:anyAtomicType*"/>
  <xsl:sequence
     select="fn:distinct-values($arg1[not(.=$arg2)])"/>
</xsl:function>Which is in
https://www.w3.org/TR/xpath-functions-31/#other-functions (Appendix D).

So basically

distinct-values($jpeg_few[not(. = $jpeg_many)]

Should give you the answer you seek.

I agree with Mike that being obsessive about putting data types on all
variables and function return values (and templates when the templates should
return atomic types or specific element types) will help a lot.

If your code is working without types but failing with them it means your code
is "working" but probably not for the reasons you think.

Working carefully through the stages of the expressions by setting each
intermediate result into variable will help a lot.

I also depend heavily on using messages to test my assumptions.

For example, I might do something like:

<xsl:message>+ [DEBUG] jpeg_few={$jpeg_few => string-join(',
')}</xsl:message>
<xsl:message>+ [DEBUG] jpeg_many={$jpeg_many => string-join(',
')}</xsl:message>

Or if those lists are very long, use count() or get the first n items or
whatever to make it clear that you're working with the values you think you
are.

Also, remember that <xsl:value-of> ({} in string result contexts) is different
from <xsl:sequence>, which returns the actual value, not a string
representation.

For example, given a variable that is an attribute node, value-of will return
string value of the attribute but xsl:sequence will return the attribute node
and Saxon will serialize it as <attribute name="foo" value="bar"> (or
something similar to that.

It's easy to accidently create a sequence of attributes when what you wanted
was a sequence of strings (or visa versa) and using xsl:value-of can obscure
that mistake.

I've also started using the XQuery-required explicating casting of values even
though XSLT usually lets you get away with implicit casting, because it makes
it clearer to me what my intent was (and makes it easier to copy XPath
expressions into XQuery, if that's something you need to do).

Cheers,

Eliot
--
Eliot Kimber
http://contrext.com


o;?On 10/14/18, 3:53 PM, "Dave Lang emaildavelang@xxxxxxxxx"
<xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

    > That error can only come from an expression that calls tokenize(). It's
therefore clearly not your declaration of jpgs_in_xml_not_directories that's
at fault.

    Fair enough - but when I run the transformation without that declaration
    everything works fine. Is there something I can do to the variables that
    are included in it to make the declaration work?