[NTG-context] passing dimensions to metapost

[Thomas A. Schmitz]

On Aug 28, 2008, at 9:45 AM, Hans Hagen wrote:

Hans, thanks a lot for your reply. Amazing - the lua code is so simple  
that even I can understand it! I'm certain to use it later; for the  
time being, I want to remain compatible for mkii and XeTeX as well.

> \startluacode
> document.mymodule = document.mymodule or { }
>
> function document.mymodule.checkdimen(str)
>     return (str:find("%a%a$") and str) or (str .. "mm")
> end
> \stopluacode
>
> \ctxlua{document.mymodule.checkdimen("#1")}
>
> or more fancy:
>
> function document.mymodule.checkdimen(str)
>     if not str:find("%a%a$") then
>         str = str .. "mm"
>         ctx.writestatus("mymodule","you forgot a dimension unit, so I
> made it up for you: %s",str)
>     end
>     return str
> end
>
> for mkii you can use \doifdimensionelse (it reminds me to implement  
> that
> in mkiv)

Hey, I WAS using \doifdimensionelse and \doifnumberelse! :-) And it  
appears to be working in mkiv as well! I found out the error in my  
code (it was too complex, and I was overwriting a variable with the  
same name; it looks like Metapost assigns "sp" as default unit to  
\MPvar). Problem solved, but it took me half a day...

All best

Thomas