On 4/10/2019 9:27 PM, Geert Verhaag wrote:
Hi,
I've the following xml file:
*<?xml version='1.0' standalone='yes?>
<content> <object mid="a"> <text>a paragraph of text</text> <value>40.2</value> </object> <object mid="b"> <text>another paragraph of text</text> <value>10.7</value> </object> <object mid="c"> <text>still another paragraph!</text> <value>20.5</value> </object> </content>*
And want to calculate the total value of all the objects:
like so:
*\startxmlsetups xml:example:base \xmlsetsetup{#1}{content|object}{xml:example:*} \stopxmlsetups
\xmlregisterdocumentsetup{example}{xml:example:base}
\startxmlsetups xml:example:content totalvalue: \xmlfunction{#1}{totalvalue} \xmlflush{#1} \endgraf \stopxmlsetups
\startxmlsetups xml:example:object attribute : \xmlatt{#1}{mid} \par \stopxmlsetups
% LUA
\startluacode function xml.functions.totalvalue(root) local score = 0 for e in xml.collected(root,"/object") do tex.write('Okay!') --score = score + xml.filter(e,"xml:///value/number()") or 0 end tex.write(score) end \stopluacode
\starttext
\xmlprocessfile{example}{content.xml}{}
\stoptext*
* *
When I run this example I get:
*totalvalue: Okay!Okay!Okay!0 attribute : a attribute : b attribute : c*
That looks allright!
But when I incorporate the line:
*score = score + xml.filter(e,"xml:///value/number()") or 0*
the following Lua error is thrown: **
*! LuaTeX error [string "\directlua "]:5: attempt to perform arithmetic on a nil value*
Has anybody any idea what I'm doing wrong here? The manual *xml-mkiv.pdf* doesn't give any clue about this! \startluacode function xml.functions.totalvalue(root) local score = 0 for e in xml.collected(root,"/object/value") do score = score + tonumber(xml.text(e)) or 0 end context(score) end \stopluacode
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