Re: [NTG-context] getting ConTeXt results back to Lua (for typesetting solutions at end of document)

31 Jan 2019

      A while back I asked a similar question, and Hans pointed out the following which I still use:

\defineenumeration
 [exercise]
 [way=bysection,
  text=Exercise,
  coupling=solution,
  location=hanging]

\defineenumeration
 [solution]
 [text=Solution,
  way=bysection,
  coupling=exercise,
  location=hanging]

\defineblock[exercise]
\defineblock[solution]
\hideblocks[solution]

\setupinteraction
 [state=start]

\starttext

\section{Main Text}

\subsection[subsec:1]{problem section 1}

\startexercise
Addition\index{addition} problem: $1+1=?$ 
\stopexercise

\beginsolution[one]
\startsolution
Answer: 2. 
\stopsolution
\endsolution

\subsection[subsec:2]{problem section 2}

\startexercise
Multiplication problem: $1\times1=?$
\stopexercise

\beginsolution[two]
\startsolution
Answer: 1.
\stopsolution
\endsolution

\page

%\reset[solution]

\section{Answers to the Problems}

\subsection{Answers to \in{section}[subsec:1]}

\useblocks[solution][one]

\subsection{Answers to \in{section}[subsec:2]}

\useblocks[solution][two]

\stoptext
...
On Jan 31, 2019, at 5:02 PM, Wolfgang Schuster  wrote:
Hi Sanjoy,
when you have a equal number of questions ans answers you can create a enumeration for each and collect the answers with the block mechanism.
At the end of the document you can flush the collected answers.
\defineblock [answer]
\defineenumeration [question]
\defineenumeration [answer]
\starttext
\startquestion
Question 1
\stopquestion
\beginanswer
\startanswer
Answer 1
\stopanswer
\endanswer
\startquestion
Question 2
\stopquestion
\beginanswer
\startanswer
Answer 2
\stopanswer
\endanswer
\page
\useblocks[answer]
\stoptext
Wolfgang
Sanjoy Mahajan schrieb am 31.01.19 um 22:51:
...
Dear List,
I'm trying to have problem solutions automatically collected, each with
its corresponding problem number, e.g. 2.3, and then typeset at the end
of a document.  Thus, I imagine something like
\startproblem{A problem title}  % Problem 1.1
A question
\startsolution
An answer
\stopsolution
\stopproblem
And then the solution(s) would appear at the end (with the "1.1"
remembered from when the problem was typeset):
  Solution to Problem 1.1.
  An answer
It seems that buffers are the way to do this.  But I cannot quite get
the automatic numbering to work.  The delayed evaluation and information
passing between lua and ConTeXt has me confused and tangled in a knot.
Below is a minimal almost-working example.  The issue is in the line
      {\ctxlua{userdata.addTempToBuffer('#1', [==[\getnumber[problem]]==])}}
which ends up putting the verbatim string "\getnumber[problem]" into the
temp buffer, rather than the typeset result, which would be something
like 1.1 or 1.2.
I've read the cld-mkiv.pdf manual, but I must be missing a simple
solution to getting ConTeXt to send back the result of
\getnumber[problem].  I've also tried the analogous
context.getnumber({"problem"}), though without success.
Does anyone see what I am missing?
Many thanks!
-Sanjoy
\defineenumeration[problem]
                  [title=yes, text=Problem, way=bychapter, prefix=chapter]
\defineenumeration[solution][problem]
\setupenumeration [solution][text={Solution to problem}, number=no]
\def\test#1{[#1]}
% appendbuffer modified from Sietse Brouwer's on mailing list (Jan 15, 2013)
\startluacode
    userdata = userdata or { }
    function userdata.addTempToBuffer(buffername, problem)
        buffers.append(
            buffername,
            '\\startsolution{' .. problem .. '}\n' .. buffers.getcontent('APPENDTEMP') .. '\n\\stopsolution\n\n'
        )
    end
\stopluacode
\def\startappendbuffer[#1]%
  {\def\stopappendbuffer%
      {\ctxlua{userdata.addTempToBuffer('#1', [==[\getnumber[problem]]==])}}
   \dostartbuffer[APPENDTEMP][startappendbuffer][stopappendbuffer]}
\starttext
\chapter{One}
\startproblem{Test}
  Test problem
\startappendbuffer[soln]
Solution
\stopappendbuffer
\stopproblem
\startproblem{Test}
Test problem
\startappendbuffer[soln]
Solution
\stopappendbuffer
\stopproblem
\typebuffer[soln]
\stoptext
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___________________________________________________________________________________

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maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
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Re: [NTG-context] getting ConTeXt results back to Lua (for typesetting solutions at end of document)

Weber, Matthias