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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