Re: Struggling with ConTeXt

[Hans Hagen <pragma@wxs.nl>]

On 3-8-2012 08:35, Olivier Binda wrote:
> On 02/08/2012 17:43, Aditya Mahajan wrote:
>> On Thu, 2 Aug 2012, Olivier Binda wrote:
>>
>>> 1) does lxml.att("#1","some tag")  really work ?
>>
>> I don't know, but please provide a complete minimal example.
> \startxmlsetups xml:test
> \xmlsetsetup{maths}{c}{xml:*}
> \stopxmlsetups
> \xmlregistersetup{xml:test}
> \startxmlsetups xml:c
> \ctxlua{
> title = "test="..lxml.att("#1","title")
> context(title)}%
> \stopxmlsetups
>
> \starttext
> test : \xmlprocessdata {maths}{<?xml version='1.0' standalone='yes?><c
> title="My title"></c>} {}
> \stoptext
> \endinput
>
> Context gives  the "can't concatenate with a nil value" Luatex error
> when processing this snipet...but if I ignore the error, the pdf output
> is okey

the functions in the lxml namespace already print to context and return 
no value so you effectively appends nil which is invalid

also, when used in a context run the default serializer is also piping 
to context so if you want otherwise you need to prefix with xml:// 
(which is an indication that in principle there can be many variants)

here are some valid solutions (whatch the lxml.id):

\startxmlsetups xml:test
     \xmlsetsetup{#1}{c}{xml:*}
\stopxmlsetups

\xmlregistersetup{xml:test}

\startxmlsetups xml:c
     \ctxlua{title = "test=" .. 
xml.filter(lxml.id("#1"),"xml://./attribute(title)") context(title)}
     \par
     \ctxlua{context("test=") 
xml.filter(lxml.id("#1"),"./attribute(title)")}
     \par
     \ctxlua{context("test=") lxml.att("#1","title")}
\stopxmlsetups

\starttext

     \xmlprocessdata
       {maths}
       {<?xml version='1.0' standalone='yes?><c title="My title"></c>}
       {}

\stoptext

You can wikify this ...

Hans


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