Re: [NTG-context] calculating with dimension unit

22 Apr 2013


      Am 22.04.2013 um 10:14 schrieb Hans Hagen :
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On 4/22/2013 8:48 AM, Wolfgang Schuster wrote:
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Am 22.04.2013 um 01:13 schrieb Jan Heinen :
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In a book I produced with ConTeXt last year, I did a lot of calculation to be able to change the layout dynamicaly.
With the actual version of ConTeXt I can't compile the book. I have tried a lot of things today ... without success.
I hope my minimal-example helps you to understand, what I want to do - and what I am doing wrong:
\starttext
\setupexternalfigures[location={local,global,default}]
\defineexpandable\ColumnA    {30mm}
\defineexpandable\ColumnB    {40mm}
\defineexpandable\ColumnABi    {\dimexpr(\ColumnA + \ColumnB)}
\defineexpandable\ColumnABii   {\ctxlua{context(\ColumnA + \ColumnB)}}
\newdimen\ColumnABiii \ColumnABiii = \dimexpr(\ColumnA + \ColumnB)
\definemeasure[ColumnA][30mm]
\definemeasure[ColumnB][40mm]
\definemeasure[ColumnBi][\the\dimexpr(\measure{ColumnA}+\measure{ColumnB})]
FYI: \the\dimexpr... will look ahead till there's something nonexpandable, and contrary to what one expects
\dimexpr(...)
will not stop at the ) so, although with measures it normally goes okay, personally I always use \relax as terminator; the \relax will be eaten up so there is no interference but it guarantees to stop scanning.
AFAIR the etex already mentions it.
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(I've been wondering if we should make measured \the\dimexpr..\relax internally which can save dimexpr at the user end.)
+1

Wolfgang