Re: Feature request: Access to MP variable values from TeX/LaTeX?

>Currently `luamplib` sets the values `\MPwidth` and `\MPheight` after 
>each figure is processed to provide information about the bounding box, 
>but would it be possible to get access to the value of other variables 
>that MP has calculated?

I do not know if luamplib grants it, but if you have access to the 
internal (in lua) metapost instance, you can use the mplib.get_numeric() 
function that is mentioned on page 242 of the luatex manual.

>The `tkz-elements` package provides `\tkzUseLua` that lets you get at 
>a Lua value, so maybe there is a generic Lua way of doing this?

Here is an example with minim-mp:

-----------------------------------------------
\documentclass{article}
\usepackage{minim-mp}

\def\MPvalue#1{\directlua {
     local mp = require 'minim-mp'
     local mpi = mp.instances[\the\mpi].instance
     tex.sprint(mplib.get_numeric(mpi, '#1'))}}

\newmetapostinstance \mpi

\begin{document}

\runmetapost \mpi { n = 42; }

The value of n is \MPvalue{n}.

\end{document}
-----------------------------------------------

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