Hello Contexteers! Sometimes the necessity could arise to send data from lua to context and answers back to lua. I tried this by using "read" and "immediate\write" commands in context. These commands are described in chapter 21 and 22 of Donald E. Knuth's "The TeXbook".
My question is: Do there exist better and more simple solutions?
Here is my WE which is admittedly a little bit ugly, but it works.
Appended the pdf-output:
========================================================================
\starttext
\startluacode
tex.print("Here is lua.")
tex.print(" ")
tex.print("I'm sending some picture names to Context in order to get back their
sizes.")
local imageA = "2007-01-01---Intro.png"
local imageB = "2007-01-01---Neujahrsballade---1.png"
local imageC = "2007-01-01---Neujahrsballade---2.png"
local f = assert(io.open("contextin.txt", "w"))
f:write(imageA .. "\n" .. imageB .. "\n" .. imageC)
f:close()
\stopluacode
% -------------------------------------------------------------
\openin15=contextin.txt
\read15 to \zeileA
\read15 to \zeileB
\read15 to \zeileC
\closein15
\vskip\lineheight
=====================================================
\vskip\lineheight
Here is \CONTEXT\ and what I got from Lua:
\vskip\lineheight
\zeileA \\
\zeileB \\
\zeileC
\vskip\lineheight
Now I'm working ... and write my answers to a file for lua: \\
\zeileA\ width=3000pt height=2000pt \\
\zeileB\ width=1200pt height=900pt \\
\zeileC\ width=1600pt height=1200pt \\
\immediate\openout7=contextout.txt
\immediate\write7{\zeileA\ width=3000pt height=2000pt \\}
\immediate\write7{\zeileB\ width=1200pt height=900pt \\}
\immediate\write7{\zeileC\ width=1600pt height=1200pt \\}
\immediate\closeout7
\vskip\lineheight
=====================================================
\vskip\lineheight
% -------------------------------------------------------------
\startluacode
tex.print("Here is lua again and what I got back from Context:")
tex.print(" ")
tex.print(" ")
local f = assert(io.open("contextout.txt", "r"))
local contexts_answer = f:read("*a")
f:close()
tex.print(contexts_answer)
\stopluacode
\stoptext
========================================================================
Best regards,
Rudolf
input-test.pdf
Description: Adobe PDF document
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